Screening methods based on superactivated alpha V beta 3 integrin

ABSTRACT

The present invention is directed to a method of identifying an inhibitor or enhancer of α v β 3  activity by contacting superactivated α v β 3  integrin with one or more molecules; and assaying an α v β 3  integrin activity, where reduced α v β 3  activity identifies an inhibitor of α v β 3  activity and where enhanced α v β 3  activity identifies an enhancer of α v β 3  activity. In a preferred embodiment, a cell, such as a MCF- 7  breast carcinoma cell, is transfected with a nucleic acid molecule encoding a superactivated β 3  variant, which can have, for example, substantially the amino acid sequence of SEQ ID NO:6 shown in FIG.  3.

BACKGROUND OF THE INVENTION

[0001] This application is based on, and claims the benefit of, U.S. Provisional Application No. 60/220,706, filed Jul. 26, 2000,and entitled SCREENING METHODS BASED ON SUPERACTIVATED (Vβ3 INTEGRIN, and which is incorporated herein by reference.

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the fields of molecular medicine and anti-cancer and tissue regeneration therapeutics and, more specifically, to drugs that are inhibitors or enhancers of the function of superactivated α_(v)β₃ integrin.

[0004] 2. Background Information

[0005] The concerted action of matrix metalloproteinases (MMPs) and integrins have been implicated in a variety of processes involved in tumor progression (Coussens et al., Chemistry and Bioloqy 3:895-904 (1996); Ruoslahti, Tumor Biol. 17:117-124 (1996); Varner and Cheresh Curr. Opin. Cell Biol., 8:724-730 (1996); and Cheresh, Cancer and Metastasis Rev., 10:3-10 (1991)). The membrane-type MMPs, which include MT1-MMP, MT2-MMP, MT3-MMP, MT4-MMP, MT5-MMP and MT6-MMP are distinguished from other MMPs by the existence of a C-terminal transmembrane domain that associates MT-MMPs with the lipid membrane bilayer (Seiki, APMIS 107:137-143 (1999)). In addition to directly degrading certain components of the extracellular matrix as do other membrane-type MMPs, MT1-MMP initiates the activation pathway of secretory pro-Gelatinase A, also known as pro-MMP-2, by cleaving the pro-MMP-2 polypeptide chain at Asn₆₇-Leu₆₈ (Sato et al., Nature 370:61-65 (1994); Strongin et al., J. Biol. Chem. 268:14033-14039 (1993); Strongin et al., J. Biol. Chem. 270:5331-5338 (1995)).

[0006] Integrins are cell surface receptors that are essential for adhesion and locomotion of cells through extracellular matrix substrata and tissue barriers. 1<Integrins also play a role in neovascularization during development and tumorigenesis and are upregulated in tumors such as breast carcinomas. Thus, inhibitors of integrin-mediated cell adhesion can be effective anti-cancer therapeutic agents (Strongin et al., J. Biol. Chem. 268:14033-14039 (1993) and Friedlander et al., Science 270:1500-1502 (1995)).

[0007] One of the major integrins, Uvβ37 was demonstrated to be critically involved in locomotion and metastasis of tumor cells such as breast cancer cells (Friedlander et al., Science 270:1500-1502 (1995) and Gladson et al., Am. J. Pathol. 148:1423-1434 (1996)). The main extracellular matrix ligands of the α_(v)β₃ integrin are vitronectin and fibronectin. Binding of α_(v)β₃ to vitronectin and fibronectin, which is RGD-dependent, can be inhibited with RGD peptides including cyclopeptides and α_(v)β₃ -specific function-blocking monoclonal antibodies (Strongin et al., J. Biol. Chem. 268:14033-14039 (1993); Storgard et al., J. Clin. Invest., 103:147-154 (1999); Brooks et al., Cell, 79:1157-1164 (1994); Horton, Exp. Nephrol. 7:178-184 (1999); and Craig et al., Biopolymers 37:157-175 (1995)). However, because the molecular mechanisms involved in interactions of the integrin with its ligands are poorly understood, specific inhibitors of (XVβ3 other than antibodies or RGD peptides have not been readily identified. The present invention satisfies this need by providing a novel screening method for discovery of α_(v)β₃ -inhibiting anti-cancer therapeutics, which is based on a novel, superactivated form of α_(v)β₃. The present invention provides related advantages as well.

SUMMARY OF THE INVENTION

[0008] The present invention is directed to a method of identifying an inhibitor or enhancer of α_(v)β₃ activity by contacting superactivated α_(v)β₃ integrin with one or more molecules; and assaying an α_(v)β₃ integrin activity, where reduced α_(v)β₃ activity identifies an inhibitor of α_(v)β₃ activity and where enhanced α_(v)β₃ activity identifies an enhancer of α_(v)β₃ activity. A method of the invention is practiced by detecting an alteration in α_(v)β₃ integrin activity upon treatment of superactivated α_(v)β₃ integrin with a molecule. An α_(v)β₃ integrin activity assayed in a method of the invention can be, for example, cell adhesion activity such as vitronectin-binding activity, fibronectin-binding activity or adhesion to a function blocking α_(v)β₃ -specific antibody.

[0009] The methods of the invention can be conveniently performed as cell-based assays, in which superactivated α_(v)β₃ integrin is expressed on a cell, which can be, for example, a tumor cell or an immortalized cell and, in particular, a MCF-7 breast carcinoma cell. In one embodiment, a cell such as a MCF-7 cell is doubly transfected with a β3 encoding nucleic acid molecule and an MT1-MMP encoding nucleic acid molecule. The encoded β3 subunit can have, for example, substantially the amino acid sequence of SEQ ID NO: 2, and the encoded MT1-MMP polypeptide can have, for example, substantially the amino acid sequence of SEQ ID NO: 4. In another embodiment, a cell such as a MCF-7 cell is transfected with a nucleic acid molecule encoding a superactivated β3 variant, which can have, for example, substantially the amino acid sequence of SEQ ID NO: 6 shown in FIG. 3.

[0010] The present invention also provides a superactivated β3 variant that has substantially the amino acid sequence of a β3 subunit with a threonine analog at the equivalent of position 69 and a glutamine analog at the equivalent of position 70, where, when expressed together with an α_(v) subunit, the β3 variant forms superactivated α_(v)β₃ integrin in the absence of MT1-MMP. Such a superactivated β3 variant can contain, for example, a threonine at the equivalent of position 69 and a glutamine at the equivalent of position 70. In one embodiment, a superactivated ββ3 variant of the invention has substantially the amino acid sequence of SEQ ID NO: 6.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 shows the nucleotide (SEQ ID NO: 1) and amino acid sequence (SEQ ID NO: 2) of human β3.

[0012]FIG. 2 shows the nucleotide (SEQ ID NO: 3) and amino acid sequence (SEQ ID NO: 4) of human MT1-MMP.

[0013]FIG. 3 shows the nucleotide (SEQ ID NO: 5) and amino acid sequence (SEQ ID NO: 6) of a human β3 “double mutant.” Mutant positions are underlined. Mutations were generated by substituting A206 with C206, and substituting T209 with A209 using the corresponding nucleotide primers carrying the desired nucleotide sequence and the polymerase chain reaction. The mutant β3 integrin is distinguished from the wild-type β3 integrin by containing the amino acid substitutions Threonine69 and Glutamine70.

[0014]FIG. 4 shows expression of MT1-MMP and α_(v)β₃ in MCF7 transfected cells. Control MCF7, β3-MCF7, MT-MCF7 and β3/MT-MCF7 cells were stained with anti-α_(v)β₃ mAb LM609 (left panel) or with affinity purified rabbit anti-MT1-MMP antibodies (right panel). Open and shaded histograms show staining with corresponding control (normal rabbit IgG and murine mAb 45.6) and experimental antibodies, respectively. The x-axis represents mean fluorescence intensity; the y-axis represents cell number. Profiles are representative of several independent experiments.

[0015]FIG. 5 shows immunoblot analysis of MT1-MMP (A) and α_(v)β₃ (B) expression in MCF7 cells. Cells were surface labeled with biotin and lysed. (A) MT1-MMP was precipitated from precleared cell lysates with MT1-MMP-specific antibodies, separated by SDS-PAGE on 8% gels under reducing conditions, transferred to a membrane support and probed with avidin-peroxidase. An arrowhead points at the 62 kDa MT1-MMP band. (B) Integrins were precipitated from precleared cell lysates with mAb L230 specific to the α_(v) integrin subunit, separated by SDS-PAGE on 8% gels under non-reducing conditions, transferred to a membrane support and probed with avidin-peroxidase. Arrowheads indicate positions of the α_(v) (˜160 kDa) and β3 (90 and 95 kDa) bands. Minor 100 kDa bands in control MCF7 and MT-MCF7 cells correspond to the β5 subunit of integrin α_(v)β₅.

[0016]FIG. 6 shows MCF7 cells expressing integrin α_(v)β₃ adhere to function-blocking anti-ava3 mAb LM609. MCF7 cells (5×104 cells per well of a 96 well plate) were allowed to bind control mAb 45.6 and anti-α_(v)β₃ mAb LM609. Adherent cells were stained and absorbency (OD) was measured at 540 nm. Data are mean +/− SE from a representative experiment performed in triplicate. Control MCF7 cells are represented by closed bars; β₃-MCF7 cells are represented by open bars; MT-MCF7 cells are represented by hatched bars; and β₃/MT-MCF7 cells are represented by cross-hatched bars.

[0017]FIG. 7 shows activation of pro-MMP-2 by MCF7 cells. (A and B) Transfected cells (2×10⁵ cells per well of 24-well cluster) were incubated overnight in serum-free DMEM (0.3 ml per well). Purified pro-MMP-2 (7 ng per well, lane 1, pro-enzyme alone) was added to control MCF7, β₃-MCF7, MT-MCF7 and β₃/MT-MCF7 cells (lanes 2-5, respectively). Following overnight incubation, conditioned medium (A) and cell lysates (B) were analyzed by gelatin zymography. (C) Batimastat completely inhibits MMP-2 activation by β₃/MT-MCF7 cells. Cells were incubated in serum-free DMEM in the absence (lane 1) or presence (lanes 3 and 4) of 10 ng/ml pro-MMP-2 (lane 2, pro-enzyme alone). Batimastat was added at a final concentration of 50 μM (lane 4). Following overnight incubation, conditioned medium was analyzed by gelatin zymography. The apparent molecular masses of gelatinolytic bands corresponding to pro-MMP-2 (68 kDa), the intermediate (64 kDa), and the mature MMP-2 (62 kDa) are indicated.

[0018]FIG. 8 shows vitronectin-mediated adhesion and migration of MCF7 cells. (A) β₃-MCF7 (open circles) and β₃/MT-MCF7 (closed circles) cells (5×10⁴ cells per well of a 96 well plate) were allowed to bind vitronectin coated on plastic at 0.01-20 μg/ml. Adherent cells were stained with Crystal Violet, and absorbency (OD) was measured at 540 nm. (B-D) MCF7 cells (5×10⁴ cells per well) were plated in serum-free AIM-V medium in Transwells with the membrane undersurface coated with vitronectin at the concentrations indicated. Cells were allowed to migrate for 48 hours. Subsequently, cells that had migrated to the undersurface of the membrane were detached and counted. Data are mean +/− SE from a representative experiment performed in triplicate. (B) Migration of MCF7 cells in Transwell with the membrane undersurface coated with vitronectin at 2 μg/ml. (C) Migration of β₃-MCF7 and β₃/MT-MCF7 cells in Transwells with the membrane undersurface coated with increasing concentrations vitronectin. (D) β3-MCF7 and β3/MT-MCF7 cells were pre-incubated in AIM-V medium with and without 50 μM Batimastat. Following a 18 hour incubation, cells were plated into Transwells with the membrane pre-coated with vitronectin at 2 μg/ml. Where indicated, Batimastat was added at 100 μM to the both upper and bottom chambers of Transwells.

[0019]FIG. 9 shows adhesion of MCF7 cells to PEX. (A) MCF7 cells (5×10⁴ cells per well of a 96 well plate) were allowed to bind PEX coated at 20 μg/ml. Adherent cells were stained with Crystal Violet, and absorbency (OD) was measured at 540 nm. Data are mean +/− SE from a representative experiment performed in triplicate. (B) Control (45.6) and function-blocking mAbs specific to the α_(v) integrin subunit (L230 and L1A3) and integrin α_(v)β₃ (LM609) were used at 25 μg/ml to inhibit adhesion of β₃-MCF7 (closed bars) and β₃/MT-MCF7 (open bars) cells to PEX. Data are presented as a percentage +/− SE of maximal adherence (100%) observed with control mAb 45.6.

[0020]FIG. 10 shows immunoblot analyses of MCF7 cells. (A) β3-MCF7 (lane 1) and β₃/MT-MCF7 (lanes 2 and 3) cells were grown in the presence (+) and absence (−) of 50 μM Batimastat for 48 hours, surface labeled with biotin and lysed. Integrins were precipitated from precleared cell lysates with function-blocking mAb L230 specific to the (v integrin subunit, separated by SDS-PAGE on 8% gels under non-reducing conditions, transferred to a membrane support and probed with avidin-peroxidase. The molecular masses of 90 kDa and 95 kDa corresponding to the 3 bands are indicated. (B) Integrin α_(v)β₃ was imnunoprecipitated from lysates of surface biotinylated β₃-MCF7 and β₃/MT-MCF7 cells with control mAb 45.6 (lane 1) and function-blocking mAbs L230 and L1A3 specific to the (v integrin subunit (lane 2 and 3, respectively) and mAb LM609 specific to integrin α_(v)β₃ (lane 4). Samples were separated by SDS-PAGE on 8% gels under reducing conditions, transferred to a membrane support and probed with avidin-peroxidase. The position of the 3 band (˜105 kDa) is indicated by arrowheads.

[0021]FIG. 11 shows FACScan analysis of MCF7 breast carcinoma cells stably transfected with the double mutant β3 integrin subunit.

[0022]FIG. 12 shows migration in transwells of MCF7 breast carcinoma cells transfected with the β3 integrin subunit. (A) Migration on vitronectin. (B) Migration on fibronectin.

[0023]FIG. 13 shows adhesion to vitronectin of MCF7 breast carcinoma cells transfected with the β3 integrin subunit.

DETAILED DESCRIPTION OF THE INVENTION

[0024] MT1-MMP and integrin α_(v)β₃ are associated with discrete regions of cell surfaces and appear to functionally cooperate in activating pro-MMP-2. As disclosed herein, parental MCF-7 cells, which express no detectable levels of pro-MMP-2, MT1-MMP or integrin α_(v)β₃ but which express substantial amounts of the α_(v) subunit, were stably transfected with either MT1-MMP, the β3 integrin subunit, or both. As shown in Example I, MT1-MMP mediates modification of the β3 subunit, resulting in a shift in molecular weight from about 95 kDa to about 90 kDa (see FIG. 5). This modification correlated with functional activation of integrin α_(v)β₃, such as increased vitronectin-mediated adhesion and cell migration. In addition, the MT1-MMP-dependent functional activation of α_(v)β₃ correlated with efficient adhesion to the recombinant C-terminal domain of MMP-2 and the generation of soluble and cell surface-associated mature MMP-2 enzyme (see Examples II to IV). As further disclosed herein, “superactivated” α_(v)β₃ integrin can be produced using a β3 variant containing two amino acid substitutions relative to the wild type β3 sequence (see Example V). The results disclosed herein provide the basis for a novel screening assay for identifying inhibitors of superactivated α_(v)β₃ integrin, which can be useful, for example, as anti-cancer or anti-angiogenic agents. Such an anti-angiogenic agent can be useful in treating any of a variety of conditions characterized by increased angiogenesis including, for example, ophthalmic disorders such as diabetic retinopathy or macular degeneration.

[0025] The present invention is directed to a method of identifying an inhibitor or enhancer of α_(v)β₃ activity by contacting superactivated α_(v)β₃ integrin with one or more molecules; and assaying an α_(v)β₃ integrin activity, where reduced α_(v)β₃ activity identifies an inhibitor of α_(v)β₃ activity and where enhanced α_(v)β₃ activity identifies an enhancer of α_(v)β₃ activity. A method of the invention is practiced by detecting an alteration in α_(v)β₃ integrin activity upon treatment of superactivated α_(v)β₃ integrin with a molecule. An α_(v)β₃ integrin activity assayed in a method of the invention can be, for example, cell adhesion activity such as vitronectin-binding activity, fibronectin-binding activity or adhesion to a function blocking α_(v)β₃ -specific antibody.

[0026] The methods of the invention rely on superactivated α_(v)β₃ integrin. As used herein, the term “superactivated α_(v)β₃ integrin” or “superactivated α_(v)β₃ ”means a form of the α_(v)β₃ integrin that is significantly more active than wild type α_(v)β₃ where wild type α_(v)β₃ contains wild type full-length α_(v) and β₃ subunits. Superactivated α_(v)β₃ is characterized, in part, in that it is functionally similar to α_(v)β₃ integrin expressed in β3/MT1-MMP MCF-7 cells. For example, the adhesion efficiency to PEX of superactivated α_(v)β₃ integrin expressed in β3/MT1-MMP MCF-7 cells was substantially greater than that of cells expressing α_(v)β₃ integrin in β3-MCF-7 cells that do not express MT1-MMP and, therefore, express wild type α_(v)β₃ . Superactivated α_(v)β₃ also can be characterized, for example, by having significantly higher vitronectin-binding efficiency than wild type α_(v)β₃ or resulting in significantly higher vitronectin-mediated or fibronectin-mediated directional cell motility when expressed, for example, in MCF7 cells. A superactivated α_(v)β₃ integrin can contain a truncated form of wild type β3 subunit having a molecular weight of about 90 kDa or can contain, for example, a constitutively activated β3 variant having substantially the amino acid sequence disclosed herein in FIG. 3 as SEQ ID NO: 6. A “superactivated” β3 subunit refers to a form of the β3 subunit which, when combined with α_(v) subunit, forms superactivated integrin.

[0027] The methods of the invention can be conveniently performed as cell-based assays, in which superactivated α_(v)β₃ integrin is expressed on a cell such as an endothelial cell or a tumor cell. In one embodiment, superactivated α_(v)β₃ integrin is expressed on a tumor cell or an immortalized cell such as a MCF-7 breast carcinoma cell. In a preferred embodiment, a cell such as a MCF-7 cell is doubly transfected with a β3-encoding nucleic acid molecule and an MT1-MMP-encoding nucleic acid molecule. The encoded β3 subunit can have, for example, substantially the amino acid sequence of SEQ ID NO: 2, and the encoded MT1-MMP polypeptide can have, for example, substantially the amino acid sequence of SEQ ID NO: 4. In another embodiment, a cell such as a MCF-7 cell is transfected with a nucleic acid molecule encoding a superactivated β3 variant, which can have, for example, substantially the amino acid sequence of SEQ ID NO: 6 shown in FIG. 3.

[0028] A cell useful in the invention is any cell capable of expressing superactivated (vβ3 integrin, including immortalized cells, tumor cells or primary cells. One skilled in the art understands that, preferably, such cells express low levels of most integrins. For example, MCF-7 breast carcinoma cells express high levels of α_(v)β₃ which can act as a donor of the α_(v) integrin, and relatively low levels of other integrins and, therefore, are particularly useful in the methods of the invention. One skilled in the art further understands that cells that express low or undetectable levels of the membrane-type matrix metalloproteinase MT1-MMP and low or undetectable levels of the β3 subunit also can be particularly useful in the invention.

[0029] Tumor cells useful in the invention include human tumor cells such as breast tumor cells, melanoma cells, colon tumor cells, prostate tumor cells, glioblastoma cells, renal carcinoma cells, neuroblastoma cells, lung cancer cells, bladder carcinoma cells, plasmacytoma cells and lymphoma cells. Such cells can be genetically engineered to express superactivated integrin as disclosed herein, for example, by double transfection with SEQ ID NO: 2 and SEQ ID NO: 4 encoding nucleic acid molecules, or by single transfection with a SEQ ID NO: 6 encoding nucleic acid molecule.

[0030] Non-tumor cells such as stromal or endothelial cells also can be useful in the invention. Such cells can be genetically engineered as disclosed above to express superactivated integrin, thereby accelerating the locomotion and adhesion of these cells to various extracellular matrix substrata and facilitating blood capillary growth and blood supply in patients. Furthermore, normal cells such as pancreatic cells capable of producing active insulin can be genetically engineered as disclosed above to express superactivated integrin in order to facilitate adhesion to the proper sites in transplantation treatment of diabetic patients.

[0031] In one embodiment, a method of the invention is performed with a cell that expresses a recombinant β3 encoding nucleic acid molecule and a MT1-MMP encoding nucleic acid molecule. The β3 encoding nucleic acid molecule can encode substantially the amino acid sequence of SEQ ID NO: 2; an exemplary β3 (CD61) encoding nucleic acid molecule is provided herein as SEQ ID NO: 1 in FIG. 1 and is available as GenBank accession J02703. Additional β3 encoding nucleic acid sequences are available as GenBank accession numbers AAA52589, β05106, A26547, AAA60122, AAA35927, A60798, AAB71380, AAA52600, AAF44692, AAA67537, B36268 and AAA36121.

[0032] Integrin β3 (also known as human endothelial glycoprotein, Gβ3A, GPI11a, ITGB3, CD61 and platelet glycoprotein 3a) is the common β subunit partner of the members of the α subfamily of integrins and is generally characterized by the existence of a long extracellular domain which adheres to their ligands, and relatively short transmembrane and cytoplasmic domains that direct the integrin to the cell plasma membrane and link the integrin to the cytoskeleton of the cell, respectively. Human integrin β3 has four cysteine-rich domains, four glycosylation sites, 56 cysteine residues, and a total length of 762 amino acids with a cytoplasmic domain of 47 amino acid residues. The cysteine residues are involved in interchain disulfide bonds. Position 59 is associated with platelet-specific alloantigen HPA-1 (ZW or PL(A)). HPA1A/PL(A1) has Leu-59 and HPA-1B/PL(A2) has Pro-59.

[0033] Position 169 is associated with platelet-specific alloantigen HPA-4 (PEN or YUK). HPA-4A/PEN(A)/YUK(A) has Arg-169 and HPA-4B/PEN(B)/YUK(B) has Gln-169. HPA-4B is involved in neonatal alloimmune thrombocytopenia. Position 433 is associated with platelet-specific alloantigen MO. MO(−) has Pro-433 and MO(+) has Ala-433. MO(+) is involved in neonatal alloimmune thrombocytopenia. Position 515 is associated with platelet-specific alloantigen CA (TU). CA(−)/TU(−) has Arg-515 and CA(1)/TU(+) has Gln-515. CA(+) is involved in neonatal alloimmune thrombocytopenia.

[0034] Defects in integrin β3 are one of the causes of Glanzmann thrombastenia (GTA), an autosomal recessive disorder which is the most common inherited disease of platelets. GTA is characterized by mucocutaneous bleeding of mild to moderate severity and the inability of this integrin to recognize macromolecular or synthetic peptide ligands.

[0035] Integrin β3, in conjunction with integrin α_(v) , forms the vitronectin receptor (α_(v)β₃) This heterodimeric receptor is localized to platelets, endothelial cells, monocytes, macrophages, osteoclasts and tumor cells. The vitronectin receptor functions to mediate the adhesion of cells to vitronectin as well as a variety of extracellular matrix proteins. Receptor-protein binding is mediated by the tripeptide sequence arginine-glycine-aspartic acid (“RGD”). Activation of α_(v)β₃ can promote cellular migration and provide signals for cell proliferation and differentiation. Furthermore, upregulation of α_(v)β₃ is associated with pathological conditions such as vascular restinosis, excessive bone resorption, tumor progression, angiogenesis and macular degeneration.

[0036] Integrin β3, in conjunction with integrin α_(IIb), also forms the fibrinogen receptor (α_(IIb)β₃), which mediates platelet aggregation. This receptor is basally inactive but can be activated by several agonists, causing it to bind fibrinogen, which then forms cross-bridges to fibrinogen receptors on adjacent cells. This receptor also binds other proteins including fibronectin, von Willebrand factor and vitronectin.

[0037] The term β3 or β3 subunit encompasses a polypeptide having the sequence of the naturally occurring human β3 (SEQ ID NO: 2) and is intended to include related polypeptides including alternatively spliced forms having substantial amino acid sequence similarity to human β3 (SEQ ID NO: 2). Such related polypeptides exhibit greater sequence similarity to human β3 than to other βintegrin subunits and include alternatively spliced forms of human β3, species homologs and isotype variants of the amino acid sequences shown in FIG. 1. A β3 polypeptide generally is characterized by an extracellular ligand binding domain, a transmembrane and a cytoplasmic domain as well as cysteine-rich domains and glycosylation sites. As used herein, the term β3 polypeptide describes polypeptides generally having an amino acid sequence with greater than 50% identity, preferably greater than 60% identity, more preferably greater than 70% identity, and can be a polypeptide having greater than 75%, 80%, 85%, 90%, 95% or greater amino acid sequence identity with human β3 (SEQ ID NO: 2).

[0038] An active fragment of a β3 polypeptide also can be useful in the invention. Such an active fragment can contain, for example, the N-terminal portion of the extracellular domain such as residues 26 to 500 of SEQ ID NO: 2, which is involved in binding the matrix substrata and defines the modified phenotype of the superactivated integrin.

[0039] As used herein, the term “substantially the amino acid sequence,” when used in reference to the β3 amino acid sequence SEQ ID NO: 2, is intended to mean the sequence shown in FIG. 1 or a similar, non-identical sequence that is considered by those skilled in the art to be a functionally equivalent amino acid sequence. For example, an amino acid sequence that has substantially the same amino acid sequence as SEQ ID NO: 2 can have one or more modifications such as amino acid additions, deletions or substitutions relative to the wild type sequence of human β3 (SEQ ID NO: 2), provided that the modified polypeptide retains substantially at least one biological activity of β3, such as substantially the ability to form an α_(v)β₃ integrin that is sufficient for cell adhesion to vitronectin or fibronectin.

[0040] As set forth above, a method of the invention can be performed with a cell that expresses a recombinant β3 encoding nucleic acid molecule in combination with a MT1-MMP encoding nucleic acid molecule. Such an MT1-MMP encoding nucleic acid molecule can encode, for example, substantially the amino acid sequence of SEQ ID NO: 4; an exemplary MT1-MMP encoding nucleic acid molecule is provided herein as SEQ ID NO: 3 in FIG. 2 and is available as GenBank accession U641078. Additional MT1-MMP encoding nucleic acid sequences are available as GenBank accession numbers NM004995, D26512,×90925 and X83535.

[0041] MT1-MMP polypeptide chain generally has a modular domain structure and contains a signal peptide, propeptide domain, catalytic domain, hemopexin-like domain, transmembrane domain and cytoplasmic domain. The signal peptide is proteolytically removed during secretion and trafficking of MT1-MMP. The propeptide domain has a conserved unique PRCG(V/N)PD (SEQ ID NO: 7) sequence, in which the conserved cysteine links the catalytic zinc ion to maintain the latency of the MT1-MMP zymogen. At the C-terminal end of the propeptide, there is a processing sequence RX(K/R)R (SEQ ID NO: 8), which is susceptible to the cleavage by furin, a serine proteinase of the Golgi network

[0042] The catalytic domain (about 170 amino acids) contains a zinc binding motif HEXXHXXGXXH (SEQ ID NO: 9) and a conserved methionine, which forms a unique “Met-turn” structure. This domain consists of a five-stranded P-sheet, three a-helices and bridging loops. The catalytic domain has an additional structural zinc and 2-3 calcium ions which are required for the stability and expression of enzymatic activity. The C-terminal hemopexin-like domain (about 210 amino acid residues) has an ellipsoidal disk shape with a four bladed P-propeller structure. Each blade contains four antiparallel P-strands and an a-helix. The transmembrane domain anchors MT1-MMP to the cell surface, while the cytoplasmic domain links MT1-MMP to the intracellular compartment.

[0043] The term “MT1-MMP” is synonymous with “membrane type matrix metalloproteinase-l” and encompasses a polypeptide having the sequence of the naturally occurring human MT1-MMP (SEQ ID NO: 4) as well as related polypeptides having substantial amino acid sequence similarity to human MT1-MMP (SEQ ID NO: 4). Such related polypeptides exhibit greater sequence similarity to human MT1-MMP than to other matrix metalloproteinases and include alternatively spliced forms of human MT1-MMP, species homologs and isotype variants of the amino acid sequences shown in FIG. 2. As used herein, the term MT1-MMP polypeptide describes polypeptides generally having an amino acid sequence with greater than 50% identity, preferably greater than 60% identity, more preferably greater than 70% identity, and can be a polypeptide having greater than 75%, 80%, 85%, 90%, 95% or greater amino acid sequence identity with human MT1-MMP (SEQ ID NO: 4).

[0044] An active fragment of MT1-MMP also can be useful in the invention. Such an active fragment can contain, for example, the catalytic domain of MT1-MMP, which is involved in the proteolytic modification of integrin α_(v)β₃ disclosed herein. The catalytic domain of MT1-MMP starts downstream of the putative RRKR (SEQ ID NO: 10) furin-cleavage site and includes amino acid residues 112 to 280 of the MT1-MMP polypeptide chain shown as SEQ ID NO: 4.

[0045] As used herein, the term “substantially the amino acid sequence,” when used in reference to the MT1-MMP amino acid sequence SEQ ID NO: 4, is intended to mean the sequence shown in FIG. 2 or a similar, non-identical sequence that is considered by those skilled in the art to be a functionally equivalent amino acid sequence. For example, an amino acid sequence that has substantially the same amino acid sequence as SEQ ID NO: 4 can have one or more modifications such as amino acid additions, deletions or substitutions relative to the wild type sequence of human MT1-MMP (SEQ ID NO: 4), provided that the modified polypeptide retains substantially at least one biological activity of MT1-MMP, such as substantially the ability to degrade components of the extracellular matrix or cleavage of pro-MMP-2 (gelatinase A) at Asn₃₆-Leu_(37.)

[0046] The present invention also provides a superactivated β3 variant as well as methods which rely on a cell expressing a recombinant superactivated β3 variant. A superactivated β3 variant of the invention can have substantially the amino acid sequence of a β3 subunit with a threonine analog at the equivalent of position 69 and a glutamine analog at the equivalent of position 70, where, when expressed together with an α_(v) subunit, the β3 variant forms superactivated α_(v)β₃ integrin in the absence of MT1-MMP. Such a superactivated β3 variant can contain, for example, a threonine at the equivalent of position 69 and a glutamine at the equivalent of position 70. In one embodiment, a superactivated β3 variant of the invention has substantially the amino acid sequence of SEQ ID NO: 6.

[0047] A naturally occurring form of β3 has an asparagine (Asn) residue at position 69 and a leucine (Leu) residue at position 70. In one embodiment, the invention provides a superactivated β3 variant having substantially the amino acid sequence of a β3 subunit with a residue other than asparagine at the equivalent of position 69 or a residue other than leucine at the equivalent of position 70, or both, where, when expressed together with an α_(v) subunit, the β3 variant forms superactivated α_(v)β₃ integrin in the absence of MT1-MMP. Such a superactivated β3 variant can have, for example, a conservative or non-conservative amino acid substitution in place of asparagine at position 69 or a conservative or non-conservative amino acid substitution in place of leucine at position 70, or both, where, when expressed together with an a, subunit, the β3 variant forms superactivated α_(v)β₃ integrin in the absence of MT1-MMP. In one embodiment, such a superactivated β variant has a non-conservative amino acid substitution in place of asparagine at position 69 and a non-conservative amino acid substitution in place of leucine at position 70, where, when expressed together with an α_(v) subunit, the β3 variant forms superactivated UVβ3 integrin in the absence of MT1-MMP.

[0048] Conservative and non-conservative amino acid substitutions are well known in the art. Non-conservative substitutions are those in which the substituted residue has one or more dissimilar properties than the original amino acid, for example, a dissimilar size, hydrophobicity, polarity or charge. Asparagine, a polar residue containing a hydrogen acceptor, can be non-conservatively substituted, for example, with a non-polar residue such as alanine, valine, leucine, isoleucine, proline, methionine, phenylalanine or tryptophan; a positively or negatively charged residue such as aspartic acid, glutamic acid, lysine, arginine or histidine; or a polar residue that lacks a hydrogen-acceptor such as glycine, serine, threonine, cysteine or tyrosine, or an analog of any of these residues. Similarly, leucine, a non-polar residue, can be non-conservatively substituted, for example, with an uncharged, polar residue, or a negatively or positively charged residue. In particular, leucine can be non-conservatively substituted, for example, with any of the following residues: asparagine, cysteine, glutamine, glycine, serine, threonine, tyrosine, aspartic acid, glutamic acid, arginine, lysine, histidine or an analog of any of these residues, or a residue of a dissimilar size.

[0049] As used herein, the term “superactivated β3 variant” means a form of the β3 subunit, which, when expressed together with the a, subunit, forms superactivated UV3 integrin in the absence of MT1-MMP. Such a superactivated β3 variant can have, for example, substantially the amino acid sequence of SEQ ID NO: 6. A nucleic acid sequence encoding a β3 variant useful in the invention is provided herein as SEQ ID NO: 5 (see FIG. 3).

[0050] The term superactivated β3 variant is synonymous herein with β3 variant and encompasses a polypeptide having the sequence of the β3 variant disclosed herein as SEQ ID NO: 6 as well as related polypeptides having substantial amino acid sequence similarity to the human β3 variant (SEQ ID NO: 6). Such related polypeptides include superactivated β3 variants from other species as well as isotype variants of the amino acid sequences shown in FIG. 3. A superactivated β3 variant may be characterized by structural modification induced by MT1-MMP-dependent proteolytic cleavage of the β3 N-terminal part or substitution within residues corresponding to residues 60 to 70 of the 3 polypeptide SEQ ID NO: 2. As used herein, the term β3 variant describes polypeptides generally having an amino acid sequence with greater than 50% identity an encompasses polypeptides having greater than 60% identity, greater than 70% identity, or greater than 75%, 80%, 85%, 90% or 95% amino acid sequence identity with the human β3 variant shown in FIG. 3 (SEQ ID NO: 6), provided that the variant has a residue other than asparagine at the equivalent of position 69 and a residue other than leucine at the equivalent of position 70 and that the variant retains the activity of forming superactivated α_(v)β₃ integrin when expressed together with the α_(v) subunit in the absence of MT1-MMP.

[0051] In specific embodiments, the invention provides β3 variants having an amino acid sequence with greater than 50% identity, greater than 60% identity, greater than 70% identity, or greater than 75%, 80%, 85%, 90%, 95% amino acid sequence identity with the human β3 variant shown in FIG. 3 (SEQ ID NO: 6), provided that the variant retains Thr or an analog thereof at the equivalent of position 69 and retains Gln or an analog thereof at the equivalent of position 70 and that the variant retains the activity of forming superactivated α_(v)β₃ integrin when expressed together with the v subunit in the absence of MT1-MMP.

[0052] One skilled in the art understands that a threonine analog shares the biochemical properties of the amino acid threonine and generally is an uncharged polar amino acid having a hydroxyl group. Thus, a threonine analog can be, for example, serine, tyrosine or threonine. A threonine analog also can be an amino acid or mimetic that is biochemically more similar to threonine than to the amino acid at position 69 in wild type β3, asparagine.

[0053] Similarly, one skilled in the art understands that a glutamine analog shares the biochemical properties of the amino acid glutamine and generally is an uncharged polar amino acid having an amide group. Thus, a glutamine analog can be, for example, asparagine or glutamine. A glutamine analog also can be an amino acid or mimetic that is biochemically more similar to glutamine than to the amino acid at position 70 in wild type β3, leucine.

[0054] As used herein, the term “substantially the amino acid sequence,” when used in reference to the:3 variant amino acid sequence SEQ ID NO: 6, is intended to mean the sequence shown in FIG. 3 or a similar, non-identical sequence that is considered by those skilled in the art to be a functionally equivalent amino acid sequence. For example, an amino acid sequence that has substantially the same amino acid sequence as SEQ ID NO: 6 can have one or more modifications such as amino acid additions, deletions or substitutions relative to the wild type sequence of the human β3 variant disclosed herein (SEQ ID NO: 6), provided that the modified polypeptide retains the activity of forming superactivated α_(v):3 integrin when expressed together with the α_(v) subunit in the absence of MT1-MMP.

[0055] Furthermore, a portion of the full-length β3 variant can be sufficient to form superactivated α_(v)β₃. The amino-terminal residues 26 to 500 of the β3 integrin extracellular domain is involved in binding the matrix substrata and the modifications within the N-terminal part of integrin β3 involving residues 69 and 70 of the integrin β3 sequence induce changes in the structure of the regions of the molecule downstream of this sequence that define the modified phenotype of the superactivated integrin.

[0056] In view of the above, it is understood that limited modifications can be made without destroying the biological function of a β3 polypeptide, MT1-MMP polypeptide or a β3 variant and that only a portion of the entire primary sequence can be required in order to effect activity. For example, minor modifications of human β3 (SEQ ID NO: 2), human MT1-MMP (SEQ ID NO: 4), or the human β3 variant disclosed herein as SEQ ID NO: 6 that do not destroy polypeptide activity also fall within the definition of a 3 polypeptide, MT1-MMP polypeptide or superactivated β3 variant, respectively. Also, for example, genetically engineered fragments of these polypeptides either alone or fused to heterologous proteins such as fragments or fusion proteins that retain measurable activity in, for example, a cell adhesion assay fall within the definition of the polypeptides as defined herein.

[0057] It is understood that minor modifications of primary amino acid sequence can result in polypeptides which have substantially equivalent or enhanced function as compared to the human β3 sequence set forth in FIG. 1, the human MT1-MMP sequence set forth in FIG. 2, or the β3 variant disclosed herein in FIG. 3. These modifications can be deliberate, as through site-directed mutagenesis, or can be accidental such as through mutation in hosts harboring an encoding nucleic acid. All such modified polypeptides are included in the definition of a β3 polypeptide, MT1-MMP polypeptide or superactivated β3 variant, respectively, as long as the biological function of the parent polypeptide is retained.

[0058] The methods of the invention can be used to screen a library of molecules. As used herein, the term “molecule” means any organic molecule and includes small molecule chemicals; peptides including peptidomimetics and peptoids; proteins, including antibodies and antigen-binding fragments thereof as well as non-antibody proteins; nucleic acid molecules including oligonucleotides; oligosaccharides; lipoproteins; glycolipids; and lipids. Both peptide and non-peptide molecules can be identified according to a method of the invention, as can, for example, non-antibody small molecules, including or excluding peptides. Both naturally occurring and synthetic molecules can be screened in a method of the invention. Naturally occurring molecules are a product of nature in that the groups comprising the molecule and the bonds linking the groups are produced by normal metabolic processes.

[0059] As used herein, the term library means a collection of organic molecules. Such a library can contain, for example, a plurality of diverse organic molecules or can contain various different but related organic molecules. A library of molecules can contain a few or a large number of different molecules, varying from about two to about 10¹⁵ molecules, or about 50 to about 10¹⁵ molecules, or about 1000 to about 10¹⁵, or about 10,000 to about 10¹⁵ molecules, as desired. For diverse libraries, the complexity of the library can vary such that the library covers at 5%, 10%, 20%, 30%, 40%, 50% or more of the entire pharmacophore space. For example, the DIVERSet™ chemical library (ChemBridge, San Diego, Calif.), which covers approximately 50% of the entire pharmacophore space, can be particularly useful in the methods of the invention.

[0060] Combinatorial chemical libraries are well known in the art for identification of lead compounds with pharmacological properties that can be improved by further structural optimization and can be particularly useful in the methods of the invention. The DIVERSet™ library can be particularly useful in the methods of the invention. DIVERSet™, designed for lead generation by ChemBridge and Chemical Design Ltd. (UK), is a diverse library of hand-synthesized chemical compounds for high-throughput screening. The DIVERSet™ library is a unique set of 10,000 to 50,000 drug-like, hand-synthesized small molecules, rationally pre-selected to form a “universal” library that covers the maximum pharmacophore diversity with the minimum number of compounds and which has been shown to be useful in screening assays (Komarov et al., Science 285:1733-1737 (1999) and Stockwell et al., Chem. Biol. 6:71-83 (1999)). According to Chemix software analyses (Oxford Molecular Group, Oxford, UK), the 36,000 component DIVERSet™ library is equivalent to approximately 50% of the entire pharmacophore space. The following filters were used in generating DIVERSet™: molecular weight higher then 190 and lower then 700; organic compounds and their salts containing any other atoms except: C, H ,N, O, S ,P, F, Cl, Br, I, Na, K, Ca, Mg; compounds with carbon count less then C8; compounds containing less then 2 major heteroatoms N, 0; more then 2 nitro groups; more than 6 Cl or Br or I atoms; more than 12 F atoms; more than three CF(CF₂) groups; compounds such as carbodiimides, cyanates, thiocyanates, isocyanides, acid halides and anhydrides, azides, diazoniums, N,P,S-halo, organic perchlorates, periodates, peroxides, ozonides, phosphines and phosphonium salts, disulfides pentafluorophenylhpenol and crown ethers, diazo non heterocycles, epoxides, primary halides other than F, iodiniums, alpha-haloheterocycles and compounds containing aliphatic aldehydo N-phosphorous, P-phosphorous, quarternary ammonium groups or 5 or more CN and more then six (CF₂) groups.

[0061] Similar synthetic libraries such as PRIME-Collection, Screen-Set, CNS-Set, Express-Pick and Cherry-Pick and other related combinatorial chemical libraries could be useful in the method of the invention. For example, PRIME-Collection 2000™ is a premier molecular diversity collection of 25,000 to 100,000 hand-crafted and 100% quality proven drug-like small molecules. Compounds in this collection are specially pre-selected from around 1.5 million molecules potentially available from thousands of international sources. PRIME-Collection 2000™ combines the most advanced efforts in developing compound collections that can speed medicinal chemistry efforts. SCREEN-Set, a library of 12,000 to 24,000 diverse drug-like small molecules selected for high-throughput screening primarily by integrated medicinal chemistry expertise. A related CNS-Set represents a library that includes compounds selected to generate leads that are more amenable to optimization in therapeutic areas that require both oral activity and blood brain barrier penetration.

[0062] The methods of the invention rely on assaying for reduced or enhanced α_(v)β₃ integrin activity to identify an inhibitor or enhancer of α_(v)β₃ activity. One skilled in the art understands that an “inhibitor” of α_(v)β₃ activity can reduce α_(v)β₃ activity either directly or indirectly and can be, for example, a precursor of an active compound. Similarly, an “enhancer” of α_(v)β₃ activity can increase α_(v)β₃ activity either directly or indirectly and can be, for example, a molecule which is a precursor of an active compound.

[0063] An α_(v)β₃ integrin activity to be assayed in a screening method of the invention can be, for example, a cell adhesion activity such as vitronectin-binding activity, fibronectin-binding activity, or binding to one or more extracellular matrix proteins that bind α_(v)β₃ , including collagen type I or IV, tenascin or laminin. An assay for α_(v)β₃ integrin activity also can be adhesion to a function-blocking α_(v)β₃ -specific antibody such as LM609. Various assays for α_(v)β₃ integrin activity are well known in the art and exemplified herein in Example VII.

[0064] If desired, a population of molecules can be assayed for activity en masse or in pools. For example, to identify an α_(v)β₃ inhibitor or enhancer, a population of molecules can be assayed for the ability to inhibit cell adhesion of a MCF-7 cell expressing a recombinant β3 variant; the active inhibitory population can be subdivided and the assay repeated in order to isolate the inhibitory molecule from the population. Such screening protocols, in which compounds are assayed in pools of 10, 50, 100, 200, 500 or 1000, for example, are well within the ability of those skilled in high throughput screening technology.

[0065] The following examples are intended to illustrate but not limit the present invention.

EXAMPLE I Expression of MT1-MMP and Integrin α_(v)β₃ in MCF7 Cells

[0066] The effects of joint expression of MT1-MMP and integrin α_(v)β₃ on tumor cell functions were analyzed using a variant of the MCF7 breast carcinoma cell line devoid of pro-MMP-2, the β3 integrin subunit and MT1-MMP. Flow cytometry and immunoprecipitation experiments confirmed the absence of detectable levels of MT1-MMP or α_(v)β₃ in the parental MCF7 cells. Gelatin zymography, a method that can detect minute amounts of gelatinases, also failed to demonstrate the existence of pro-MMP-2 in medium conditioned by MCF7 cells.

[0067] To induce expression of MT1-MMP and integrin α_(v)β₃, MCF7 cells were stably transfected with the MT1-MMP and 3 cDNAs, respectively. The parental cells were first transfected with either the original pcDNA3-neo plasmid or the pcDNA3-neo plasmid carrying the 3 cDNA gene. Selected neo-MCF7 and β₃-MCF7 cells were then each transfected with either the original pcDNA3-zeo plasmid or the pcDNA3-zeo plasmid carrying the MT1-MMP cDNA gene. The resulting doubly transfected cell lines expressed none (control MCF7), one of each (β₃-MCF7 and MT-MCF7), or both 3 and MT1-MMP (β₃/MT-MCF7).

[0068] Flow cytometry and immunoprecipitation analyses confirmed high levels of surface expression of MT1-MMP and (X,3 in the corresponding MCF7 cell lines (FIGS. 1 and 2). MT1-MMP expression was observed in MT-MCF7 and β₃/MT-MCF7 cells whereas control MCF7 and β₃-MCF7 cells did not demonstrate any significant expression of cell surface MT1-MMP (FIG. 4, right panel). As shown in FIG. 5A (lanes 3 and 4), MT1-MMP specific antibodies efficiently immunoprecipitated a 62 kDa biotinylated protein from MT1-MMP-transfected MCF7 cells, which correlates well with the known molecular mass of MT1-MMP (Hoekstra et al., Curr. Med. Chem. 5:195-204 (1998) and Kerr et al., Anticancer Res. 19:959-968 (1999)).

[0069] High expression of U,β3 was observed in β₃-MCF7 and L₃/MT-MCF7 cells, both of which were transfected with the 3 integrin subunit (FIG. 4, left panel; FIG. 5B, lanes 2 and 4). In contrast, no 3 was demonstrated in control MCF7 and MT-MCF7 cells (FIG. 4, left panel; FIG. 5B, lanes 1 and 3). Relatively minor bands with an approximate molecular mass of 100 kDa (FIG. 5B), correspond to the β5 integrin subunit (Wayner et al., J. Cell Biol. 113:919-929 (1991)) and correlate with expression of α_(v)β₅ in the parental MCF7 cell line. As opposed to control MCF7 and MT-MCF7 cells, the P integrin subunit with a molecular mass of 95 kDa, characteristic of the 3 subunit (Cheresh et al., Cell 57:59-69 (1989)), was readily precipitated from β₃-MCF7 cells (FIG. 5B, lane 2). The apparent molecular mass of the β3 subunit precipitated from β₃/MT-MCF7 cells, 90 kDa, was about 5 kDa less than that of the 95 kDa β3 subunit in β₃-MCF7 cells (FIG. 5B, lane 4).

[0070] The functionality of integrin α_(v)β₃ expression in MCF7 cells was analyzed by evaluating adhesion of cells to the function-blocking α_(v)β₃-specific monoclonal antibody (mAb) LM609. No adhesion of cells was observed with control mAb 45.6, and, as expected, control MCF7 and MT-MCF7 cell lines, which both lack integrin α_(v)β₃, did not adhere to anti-α_(v)β₃ mAb LM609. However, as shown in FIG. 6, β₃-MCF7 and β₃/MT-MCF7 cell lines efficiently adhered to mAb LM609, confirming that functional integrin α_(v)β₃ was expressed in cells transfected with the β3 integrin subunit.

[0071] Proteins and antibodies were prepared as follows. Pro-MMP-2, essentially free of TIMP-2, was isolated from the conditioned medium of β2AHT2A72 cells (Strongin et al., J. Biol. Chem. 268:14033-14039 (1993)). Vitronectin was a kind gift of Dr. R. DiScipio. The recombinant C-terminal domain of MMP-2 (PEX) was isolated as a FLAG-fusion protein from the periplasmic fraction of E. coli (Strongin et al., J. Biol. Chem. 270:5331-5338 (1995)). Control monoclonal antibody (mAb) 45.6 (ATCC, Rockville, MD) and mAbs specific to the α_(v) integrin subunit, L1A3 (Deryugina et al., Hybridoma 15:279-288 (1996)) and L230 (ATCC), were purified from media conditioned by corresponding hybridoma cells. Control rabbit IgG, rabbit antibodies against MT1-MMP, and murine mAb LM609 specific to integrin α_(v)β₃ were from obtained Chemicon (Temecula, Calif.).

[0072] Gelatin zymography was performed as follows. Cells were plated at 2×10⁵ cells per well of a 24-well cluster. After overnight incubation, 0.3 ml of serum-free DMEM supplemented with purified pro-MMP-2 (10 ng/ml) was added to each well. To visualize the activity of secretory MMP-2, medium conditioned by cells for 18-24 hours was mixed 1:1 with 2×SDS sample buffer and 12 μl were loaded per lane of a precast zymography gel (Novex, San Diego, Calif.). To analyze the activity of cell-associated MMP-2, 4×10⁵ cells were lysed in 35 μl of 2×SDS sample buffer, incubated for 30 min at 37° C. and mixed 1:1 with 50% glycerol. A total of 14 μl was loaded per lane of a zymography gel. Following electrophoresis, zymography gels were incubated in 2.5% Triton X-100 and then overnight at 37° C. in the developing buffer (Novex). The bands of gelatinolytic activity were revealed after staining the gels with Coomassie Blue. When identical samples are run in replicates or different samples from a particular cell line are examined, zymography analysis demonstrates very low variability, thereby allowing quantitative as well as qualitative analysis of MMP-2 activation.

[0073] Flow cytometry was performed as follows. Cells were stained with 5 μg/ml rabbit anti-MT1-MMP antibodies or murine mAb LM609 specific to avβ3 (Deryugina et al., J. Cell Sci. 110:2473-2482 (1997); Deryugina et al., Cancer. Res. 58:3743-3750 (1998)). Cells were subsequently incubated with a FITC-conjugated F(ab′)₂ fragment of goat anti-rabbit or sheep anti-mouse IgG (Sigma, St. Louis, Mo.). Viable cells were analyzed on a FACScan flow cytometer (Becton Dickinson, Mountain View, Calif.). Population gates were set by using cells incubated with normal rabbit IgG or control murine mAb 45.6.

[0074] Immunoprecipitation and Western blotting were performed as follows. Confluent cells were surface biotinylated with 0.1 mg/ml of Sulfo-NHS-LC-Biotin (Pierce, Rockford, Ill.). Where indicated, the cells were incubated prior to biotinylation with 50 μM Batimastat for 48 hours in AIM-V medium (GibcoBRL). Cells were solubilized at 10⁷/ml in lysis buffer (50 mM n-octyl-(-D-glucopyranoside in 50 mM TBS, pH 7.4/1 mM CaCl₂/1 mM MgCl₂/1 mM PMSF/10 μg/ml leupeptin/10 μg/ml pepstatin) for one hr on ice. Insoluble material was removed by centrifugation. Supernatants were precleared for two hours at 4° C. with Protein A-Agarose (Calbiochem, La Jolla, Calif.). Precleared supernatants (100-150 μl) were incubated overnight at 4° C. with 3 μg of the indicated antibodies. The immune complexes were collected on Protein A-Agarose 15 μl of a 50% slurry) during a two hour incubation at room temperature. Following washes with washing buffer (50 mM Tris, pH 7.4/0.5 M NaCl/0.1% Tween 20), the beads were treated with 4% SDS in 125 mM Tris, pH 6.8/20% glycerol buffer, and boiled. Eluted proteins were separated by electrophoresis on a 8% acrylamide gel (Novex) under reducing or non-reducing conditions, transferred onto a Immobilon-P membrane (Millipore, Bedford, Mass.), and biotin-labeled material was visualized by using avidin conjugated to horseradish peroxidase (Sigma) and TMB/M solution containing 3,3′5,5′-tetramethylbenzidine and hydrogen peroxide (Chemicon).

EXAMPLE II MT1-MMP and Integrin a9,3 Functionally Cooperate in Activation of PRO-MMP-2 to the Fully Mature Enzyme

[0075] The docking and activation of exogenous MMP-2 at tumor cell surfaces were analyzed in cells jointly expressing MT1-MMP and integrin α_(v)β₃. Pro-MMP-2, essentially free of TIMP-2, was added at 10 ng/ml in serum-free DMEM to MCF7 transfected cells (FIG. 7A and 7B, lane 1). After an overnight incubation, medium conditioned by cells was collected, and the cells were washed free of culture medium and lysed. Aliquots of conditioned medium and cell lysates were analyzed by gelatin zymography (FIGS. 4A and 4B, respectively).

[0076] As shown in FIG. 7A, lanes 2 and 3, control MCF7 and β₃-MCF7 cells did not activate exogenous 68 kDa pro-MMP-2. In contrast, MT-MCF7 cells processed the 68 kDa pro-MMP-2 to the 64 kDa activation intermediate and to some extent to the 62 kDa enzyme. Significantly higher levels of mature MMP-2, relative to those from MT-MCF7 cells, were identified in medium conditioned by β₃/MT-MCF7 cells (FIG. 7A, lanes 4 and 5). As shown by FACS (FIG. 1, right panel) and immunoprecipitation (FIG. 5A) analyses, levels of MT1-MMP expression in MT-MCF7 cells are comparable to those found in β₃/MT-MCF7 cells. These results indicate that expression of α_(v)β₃ in β₃/MT-MCF7 cells facilitates maturation of MMP-2. Incubation of β₃/MT-MCF7 cells with 50 μM Batimastat, a potent inhibitor of matrix metalloproteinases, resulted in complete inhibition of MT1-MMP and conversion of 68 kDa pro-MMP-2 to the 64 kDa intermediate (FIG. 7C, lane 4), indicating that MT1-MMP initiates the first, 68 to 64 kDa, stage of pro-MMP-2 activation while expression of α_(v)β₃ facilitates the second, 64 to 62 kDa, step of MMP-2 maturation.

[0077] Zymography analysis of cell lysates was performed to analyze the species of MMP-2 associated with MCF7 cells jointly expressing MT1-MMP and (vX3 While no gelatinolytic activity was observed in lysates of control and β₃-MCF7 cells (FIG. 7B, lanes 2 and 3, respectively), lysates of MT-MCF7 and β₃/MT-MCF7 cells demonstrated the surface bound 68 kDa proenzyme and two activated species of MMP-2, the 64 kDa intermediate and the 62 kDa fully mature enzyme (FIG. 7B, lanes 4 and 5). Of the species in β₃/MT-MCF7 cell lysates, the 62 kDa mature enzyme was the most dominant. The higher levels of MMP-2 enzyme found in β₃/MT-MCF7 cells relative to β₃-MCF7 cells indicate that expression of integrin α_(v)β₃ facilitates the MT1-MMP-induced activation of MMP-2 to the mature enzyme.

EXAMPLE III MT1-MMP Mediates Functional Activation of Integrin α_(v)β₃ in MCF7 Cells

[0078] These results demonstrate that the α_(v)β₃ integrins in β₃-MCF7 and β₃/MT-MCF7 cells differ functionally in their ligand-binding capability.

[0079] To address whether joint expression of MT1-MMP and integrin α_(v)β₃ affects the adhesion and motility of tumor cells, the vitronectin-binding efficiency of two β₃-transfected MCF7 cell lines was compared. For the cell binding assays, β₃-MCF7 and β₃/MT-MCF7 cells were allowed to adhere to increasing concentrations of vitronectin coated on plastic. Although both cell lines attached to vitronectin in a dose-dependent manner, β₃/MT-MCF7 cells demonstrated greater adhesion efficiency relative to that of β₃-MCF7 cells, especially at moderate concentrations of the ligand. As shown in FIG. 8A, 50% maximal adhesion of β₃-MCF7 cells was achieved at 5-10-fold greater coating concentration of vitronectin as compared to the coating concentration required by β₃/MT-MCF7 cells (0.3-0.5 μg/ml vs. 0.05-0.06 μg/ml, respectively). Both cell lines were selected for maximal α_(v)β₃ expression by flow cytometry (FIG. 4, left panel) and express similar levels of integrin α_(v)β₃, as shown by immunoprecipitation (FIG. 5B), indicating that the two cell lines have a similar number of integrin α_(v)β₃ sites. In particular, mean fluorescence intensity after staining of β₃-MCF7 and ₃/MT-MCF7 cells with mAb LM609 was 38.7+/−5.6 and 35.5+/−7, respectively, a difference that was statistically not significant (t=0.896, p=0.394 at the 0.05 level in the paired Student test, n=11). These results indicate that the α_(v)β₃ integrin in the β₃/MT-MCF7 cells differs in its affinity for vitronectin as compared to the α_(v)β₃ integrin in β₃-MCF7 cells.

[0080] To determine the relative contribution of integrin α_(v)β₃ and MT1-MMP to cell motility, the efficiency of transfected cells in directional migration was evaluated in Transwells in which the membrane undersurface was coated with vitronectin. As shown in FIG. 8B, the migration of control MCF7 and MT-MCF7 cells was relatively modest, with only 3-6×10³ cells, or 6-12% of cells plated per well, transmigrating across the filter in 48 hours. Furthermore, β₃-MCF7 cells, which express integrin α_(v)β₃, also did not migrate in the Transwell assay. In six independent experiments, an average of 3.3+/−0.4×103 cells (n=18), or 5.8-7.4% of 50×10³ cells plated per well, migrated onto the vitronectin-coated membrane undersurface. In contrast, the migration efficiency of β₃/MT-MCF7 cells was substantially higher, with 23.3+/−2.1×103 cells (n=21), or 42.4-50.8% of cells plated per well, migrating to the vitronectin-coated membrane undersurface. These data corroborate the vitronectin-binding data disclosed above and demonstrate that the α_(v)β₃ integrins in β₃-MCF7 and β₃/MT-MCF7 cells are functionally distinct in their ability to mediate directional cell migration on vitronectin.

[0081] As further shown in FIG. 8C, the migration efficiency of β₃/MT-MCF7 cells far exceeded that of β₃-MCF7 cells in experiments where cells migrated in Transwells with the undersurface coated with increasing concentrations of vitronectin. While the migration of β₃-MCF7 cells was relatively low and did not increase proportionally relative to increasing concentrations of vitronectin, the migration of β₃/MT-MCF7 cells was dose-dependent in a concentration range from 0.1 to 5 μg/ml vitronectin. Taken together, these data demonstrate the functional activation of integrin α_(v)β₃ in β₃/MT-MCF7 cells.

[0082] MT1-MMP activity was examined relative to the functional activation of integrin α_(v)β₃ in ₃/MT-MCF7 cells. After first incubating β₃-MCF7 and β₃/MT-MCF7 cells for 18 hours in serum-free AIM-V medium, the cells were allowed to migrate in Transwells with and without Batimastat for 48 hours. As shown in FIG. 8D, Batimastat, if added directly to Transwells, did not significantly affect the migration of β₃/MT-MCF7 cells. However, if β3/MT-MCF7 cells were pre-incubated with Batimastat for 18 hours and then allowed to migrate in the presence of the inhibitor, cell migration was strongly inhibited. These results indicate that the functional activation of integrin α_(v)β₃ in β₃/MT-MCF7 cells is MT1-MMP-dependent.

[0083] In sum, these data indicate that MT1-MMP mediates the functional activation of integrin α_(v)β₃ in MCF7 cells and thereby facilitates the ligand-specific attachment and migration of these cells. These results further indicate that MT1-MMP and integrin avβ3 contribute jointly, but not individually, to the efficient directional locomotion of MCF7 cells.

[0084] The directional migration of cells in Transwells (Costar, Cambridge, Mass.) was analyzed under serum-free conditions (Deryugina et al., supra, (1997)) essentially as follows. The undersurface of a 6.5 mm insert membrane with a 8 micron pore size was coated with vitronectin. Cells detached with enzyme-free buffer (Specialty Media, Lavalette, N.J.) were plated into the insert at 5×10⁴ in 0.15 ml AIM-V medium. The outer chamber was filled with 0.5 ml of AIM-V medium. Following a 48 hour incubation, cells that migrated to the membrane's undersurface were detached with trypsin/EDTA and counted.

[0085] Adhesion assays were performed as follows using high binding 96-well plates (Corning, Corning, N.Y.) pre-coated with vitronectin (from 0.01 to 20 μg/ml), PEX (20 μg/ml) or mfAb LM609 (2 μg/ml) (Deryugina et al., supra, (1997); Deryugina et al., supra, (1998)). Cells (5×10⁴ cells per well in 0.1 ml of DMEM/1%BSA/20 mM HEPES buffer, pH 7.2) were allowed to bind to plastic coated with vitronectin or Inabs for 1 hour and with PEX for 8 hours at 37° C. in a CO₂-incubator. Function-blocking anti-integrin mabs were used at a final concentration of 25 μg/ml. Bound cells were stained with Crystal Violet. The incorporated dye was extracted with 100 mM sodium phosphate/50% ethanol, pH 4.5 before measuring absorbance at 540 nm.

EXAMPLE IV Activated Integrin α_(v)β₃ Binds MMP-2 Via the PEX Domain

[0086] Integrin α_(v)β₃ binds the recombinant C-terminal domain of MMP-2 (PEX; Brooks et al., Cell 85:683-693 (1996)), allowing tumor cells to bind to PEX (Deryugina et al., supra, (1997)). The MT1-MMP-mediated activation of integrin α_(v)β₃ was analyzed relative to MMP-2 docking at cell surfaces by evaluating the adhesion of MCF7 cells to PEX. Cells were allowed to bind for 8 hours to PEX coated on plastic at 20 μg/ml. Whereas almost no binding to PEX was observed with control and MT-MCF7 cells, expression of the α_(v)β₃ integrin correlated with the ability of cells (β₃-MCF7 and β₃/MT-MCF7) to adhere to PEX. As shown in FIG. 9A, the adhesion efficiency of β₃/MT-MCF7 cells was substantially greater than the adhesion of 3-MCF7 cells. Cell adhesion was blocked by the α_(v)β₃-specific mAb LM609 and by two αv-specific mAbs, L230 and L1A3, confirming that integrin α_(v)β₃ mediates the binding of β₃-MCF7 and β₃/MT-MCF7 cells to PEX (see FIG. 9B). These findings indicate that the MT1-MMP-mediated activation of integrin α_(v)β₃ promotes the docking of MMP-2 via its C-terminal domain at the α_(v)β₃ cell surface sites. In turn, docking can facilitate activation of MMP-2 to the mature enzyme by cells simultaneously expressing integrin α_(v)β₃ and MT1-MMP.

EXAMPLE V MT1-MMP-DEPENDENT Modifications of the β3 Integrin Subunit

[0087] Functional properties of activated integrin α_(v)β₃ were analyzed for a possible association with one or more structural modifications of β3 subunit. In particular, electrophoretic and immunological characteristics of the β3 integrin subunit from β₃-MCF7 and β₃/MT-MCF7 cells were compared by immunoprecipitation with mabs specific to α_(v) (L230 and L1A3) or α_(v)β₃ (LM609) integrins. As was shown in FIG. 5B, there is a 5 kDa difference in the molecular masses of the β3 integrin subunit precipitated from β₃-MCF7 and β₃/MT-MCF7 cells (FIG. 5B, lanes 2 and 4). These results indicate that MT1-MMP can mediate a proteolytic modification of the 3 integrin subunit.

[0088] To verify the proteolytic nature of modification of the 3 integrin subunit, β₃/MT-MCF7 cells were incubated with Batimastat to block metalloproteinase activity. As shown in FIG. 7C, Batimastat at a 50 μM concentration completely inhibited the MT1-MMP-induced activation of MMP-2 by β₃/MT-MCF7 cells. Without the inhibitor, the exogenously added 68 kDa pro-MMP-2 (FIG. 7C, lane 2) was efficiently converted into the 64 kDa intermediate and 62 kDa mature enzyme (FIG. 7C, lane 3). In contrast, in the presence of Batimastat, exogenous pro-MMP-2 remained a zymogen in β₃/MT-MCF7 cultures (FIG. 7C, lane 4), indicating that Batimastat completely inhibits MT1-MMP-dependent activation of MMP-2.

[0089] Furthermore, β₃-MCF7 and β₃/MT-MCF7 cells, incubated with and without 50 βM Batimastat for 48 hours, were surface labeled with biotin and lysed. Thereafter, αv integrins were immunoprecipitated from cell lysates with mAb L230 and analyzed by Western blotting. As shown in FIG. 10A, the apparent molecular mass of the β3 integrin subunit from β₃/MT-MCF7 cells incubated with Batimastat shifted to a 95 kDa value characteristic of the “wild-type” β3 from β₃-MCF7 cells (FIG. 10A, lanes 1 and 3). Thus, inhibition of MT1-MMP activity by Batimastat abolished the one or more modifications which account for the higher electrophoretic mobility of the 3 integrin subunit from β₃/MT-MCF7 cells.

[0090] To analyze whether MT1-MMP expression affects the immunological characteristics of the β3 integrin subunit, immunoprecipitation profiles of β3 precipitated from β₃-MCF7 and β₃/MT-MCF7 cells with mAbs L1A3 and L230, specific to the α_(v) integrin subunit, and mAb LM609 specific to integrin Uβ3, were compared. While the β3 integrin subunit was efficiently immunoprecipitated from β₃-MCF7 cells with all anti-integrin mAbs used, almost no 3 was observed in β₃/MT-MCF7 cells after precipitation with mAb LM609 (FIG. 10B). These findings indicate that the LM609 binding site of the β3 integrin subunit is modified in β₃/MT-MCF7 cells.

[0091] In sum, these data demonstrate that MT1-MMP mediates one or more modifications of the β3 subunit and that such modifications correlate with functional activation of integrin α_(v)β₃. These data further indicate that, by facilitating directional cell migration and MMP-2 binding at cell surfaces, functional activation of integrin α_(v)β₃ can be an important event in tumor invasion and metastasis.

EXAMPLE VI Production and Characterization of a Constitutively Superactivated Form of the β3 Integrin

[0092] Production and Characterization of of a β3 Double Mutant

[0093] The β3 double mutant was prepared by PCR using the corresponding oligonucleotide primers. Mutagenesis to insert the N→T and L→Q substitutions at the position 69 and 70 of the β3 chain, respectively, were done by using the 204-GACTCAGCTGAAGGATAACTGTGCCCC-230 (SEQ ID NO: 11) direct primer and the 203-TCCTTCAGGTCACAGCGAGGTGAGCCC-177 (SEQ ID NO: 12) reverse primer (mutated positions shown by underlining in FIG. 3). The resulting mutant HindIII/XbaI fragment was recloned into pcDNA3-neo. MCF7 breast carcinoma cells were stably transfected with the recombinant pcDNA-3-neo plasmid carrying the double β3 mutant insert by standard methods. Stable transfectant clones were selected by flow cytometry employing integrin βvβ3 specific LM609 monoclonal antibody. Flow cytometry experiments were performed as described above in Example 1. FIG. 11 demonstrates FACS analysis of MCF7 breast carcinoma cells stably transfected with the double mutant β3 integrin subunit. I

[0094] To determine the effect of mutation on cell motility, the efficiency of MCF7 cells transfected with the wild type and double mutant β3 subunit was evaluated in Transwells in which the membrane undersurface was coated with 2 μg/ml vitronectin and 5 μg/ml fibronectin (see FIG. 12). The migration assays were executed as described above in Example III. As shown in FIG. 12, migration of cells transfected with the double β3 mutant was significantly higher than that of control MCF7 cells and MCF7 cells transfected with the wild type β3 subunit.

[0095] To evaluate the effect of mutation on cell adhesion, cells expressing the wild type and the double β3 mutant were allowed to adhere to plastic pre-coated with increasing concentrations of vitronectin. The experiments were performed under experimental conditions described in Example III. As shown in FIG. 13, cells expressing the mutant β3 integrin demonstrated greater adhesion efficiency relative to that of cells expressing the wild type β3 integrin. These findings indicate that the functional properties of the β3 double mutant correspond to those observed in cells doubly transfected with MTI-MMP and the wild type β3 integrin. Thus, integrin α_(v)β₃ bearing the double β3 mutant integrin subunit can be classified as a superactivated integrin exactly as integrin α_(v)β₃ modified by MT1-MMP in β3/MT-MCF7 doubly transfected cells.

EXAMPLE VII Screening for Agonists and Antagonists of Superactivated α_(v)β₃

[0096] Doubly transfected β3/MT1-MMP-MCF7 cells expressing superactivated integrin α_(v)β₃ prepared as described above are utilized in the assay. Neo/zeo-MCF7 cells transfected with both neo-pcDNA3 and zeo-pcDNA3 plasmids with no inserts are used as the control. Prior to plating cells, individual chemicals in DMSO (1 ml) from corresponding stock solutions of the DIVERSet™ library (ChemBridge) are added directly to wells of a 96 well plate to a final concentration of 10-30 μM. Inhibition of cell adhesion identifies useful therapeutic candidates, which are re-assayed in the concentration range 0.1-10 μM. Since the half-life of α_(v)β₃ receptors on cell surfaces is about 24 hours (Delcommenne and Streuli, J. Biol. Chem. 270:26794-26801 (1995)), metabolic modifications do not affect the results of the one-hour assay.

[0097] Results are interpreted as follows. Reduction of adhesion of β3/MT1-MMP-MCF7 cells but not of control neo/zeo-MCF7 cells to vitronectin after a one hour incubation period identifies the library member as a specific α_(v)β₃ inhibitor. Little or no toxic effect is seen on control MCF7 cells for a specific α_(v)β₃ inhibitor.

[0098] Reduction in adhesion of both neo/zeo-MCF7 and β3/MT1-MMP- MCF7 cells is indicative of an indirect effect on the α_(v)β₃ a nonspecific effect on tumor cell membranes, or a toxic effect on tumor cells. Increased adhesion of β3/MT1-MMP-MCF7 upon treatment with a library member that does not affect adhesion of control neo/zeo-MCF7 cells identifies the library member as an enhancer of α_(v)β₃ functional activity. Such a compound can be useful, for example, in tissue regeneration.

[0099] Cell culture is performed as follows. β3/MT1-MMP-MCF7 and neo/zeo-MCF7 cells are maintained routinely in DMEM/FCS supplemented with the appropriate selective antibiotic (zeocin or G418). Prior to addition of :+library compounds to be assayed, cells are incubated in serum free media for 18 to 24 hours. Cells are harvested with an enzyme-free buffer, washed and re-suspended in serum-free DMEM or AIM-V media for subsequent assays.

[0100] Cell adhesion assays are performed in high binding 96-well plates (Corning) as follows. The wells are pre-coated with 0.1 μg/ml vitronectin in PBS (Deryugina et al., J. Cell Sci. 110:2473-2482 (1997) and Deryugina et al., Cancer Res. 58:3743-3750 (1998)), which is the concentration of vitronectin shown to be most efficient in discriminating α_(v)β₃-mediated cell adhesion relative to that of control cells (see, also, FIG. 8. Prior to addition of test compounds, the wells are blocked by addition of 1% BSA. Test compounds (1 μl in DMSO from the corresponding 10-200 μM stocks) are added to cells (5×10⁴ cells per well in 0.1 ml of DMEM/1%BSA/20 mM HEPES buffer, pH 7.2), which are incubated for 1 hour at 37° C. in a CO₂-incubator. Cells are stained with Crystal Violet to detect bound cells. The incorporated dye is extracted with 100 mM sodium phosphate/50% ethanol, pH 4.5, and absorbency measured at 540 nm. Cells are plated in the presence of 1% DMSO as a negative control. In addition, cells are treated with 1 mg/ml of RGD-peptide or 25 μg/ml of function blocking α_(v)β₃-specific LM609 rAb (Chemicon International, Temecula, Calif.) for use as positive controls. This assay also can be performed with 96-well plates pre-coated with other major individual extracellular matrix proteins such as collagen type I or IV, tenascin or laminin.

[0101] Cell adhesion assays also are performed on plastic coated with the α_(v)β₃-specific function-blocking monoclonal antibody, LM609. Plates are coated with anti-mouse polyclonal antibodies at 5-10 μg/ml, and subsequently with anti-α_(v)β₃ LM609 mAb at 0.5-1 μg/ml. Cell adhesion experiments then are performed as described above. Since only cells expressing integrin α_(v)β₃ are adhesive under these experimental conditions, this assay facilitates specific and direct identification of α_(v)β₃ antagonists by observing inhibition of adhesion of β3/MT1-MMP-MCF7 cells. The use of function-blocking αv- (clones NKI-M9 and AV1), β3- (clone B3A)- and α_(v)β₃-specific antibodies (clone P1F6; all clones from Chemicon International, Temecula, Calif.) also can be used to facilitate specific identification of α_(v)β₃ antagonists.

[0102] A standard chromium-51 release assay is used to evaluate cytotoxicity of inhibitors of superactivated α_(v)β₃. Cytotoxicity found in both control neo/zeo- and β3/MT1-MMP-MCF7 cells at an LD₅₀ that is 100 times the ID₅₀ for inhibition of adhesion to vitronectin signifies a non-integrin mediated nonspecific and undesirable effect. Cytotoxicity not found in control cells but found in β3/MT1-MMP-MCF7 cells indicates a specific integrin-mediated effect that can be apoptotic in nature. Further LD₅₀ experiments are performed under in vivo conditions.

EXAMPLE VIII Further Characterization of Antagonists of Superactivated α_(v)β₃

[0103] Cell-based in Vitro Assays

[0104] If desired, antagonists of superactivated α_(v)β₃ can be further characterized using cell-based in vitro assays to determine their efficiency in blocking cell migration, invasion and proliferation.

[0105] Cell proliferation is assayed as follows using the ³H-thymidine incorporation method. Control neo/zeo- and β3/MT1-MMP-MCF7 cells are seeded into 96-well plates (3-5×10³ cells/well) and incubated with and without the antagonists of superactivated α_(v)β₃ in serum-containing and serum-free media. Following one to two days of incubation at 37° C., cell cultures are pulsed with 0.5 mCi/well of ³H-thymidine for the last 2 to 6 hours, and then washed and lysed. After transferring cell lysates onto glass filters, the incorporated ³H-thymidine is counted by standard methods.

[0106] A two-dimensional spheroid outgrowth assay employing control neo/zeo- and β3/MT1-MMP-MCF7 cells is performed with and without antagonists of superactivated UVβ3 on different ECM proteins, such as vitronectin, fibronectin, collagen type I and IV, tenascin and laminin substrates as described earlier (Deryugina et al., J. Cell Sci. 109:643-652 (1996)).

[0107] Cell migration (haptotactic) and Matrigel invasion assays are performed as follows. The migratory characteristics of control neo/zeo- and β3/MT1-MMP-MCF7 cells also are assessed in 6.5 mm Transwells (8 mm pore size), with the membrane undersurface coated with individual ECM proteins such as vitronectin, fibronectin, collagen type I or IV, tenascin or laminin. Cell invasion assays are performed in Transwells with the membrane pores occluded with Matrigel as described in Deryugina et al., Anticancer Res. 17:3201-3210 (1997).

[0108] Apoptotic effects of antagonists of superactivated α_(v)β₃ are evaluated using conventional methods involving BrdU, TUNEL and Annexin V in tissue cell cultures and by flow cytometric analyses.

[0109] MMP-2 binding activity of superactivated α_(v)β₃ treated with an antagonist is evaluated as follows. Superactivated α_(v)β₃ specifically binds MMP-2 via the C-terminal hemopexin-like (PEX) domain of MMP-2 (Deryugina et al., Int. J. Cancer 86:15-23 (2000); Brooks et al., Cell 92:391-400 (1998); and Brooks et al., Cell 85:683-693 (1996)). To evaluate whether the MMP-2 binding activity of superactivated α_(v)β₃ is affected by antagonists, β3- and β3/MT1-MMP-MCF7 cells expressing “wild-type” and “superactivated” α_(v)β₃, respectively, and non-adherent neo/zeo control cells (negative control) are assayed with and without antagonists by adhesion on plastic coated with recombinant PEX at 20 μg/ml as described previously (Deryugina et al., Int. J. Cancer 86:15-23 (2000) and Deryugina et al., J. Cell Sci. 110:2473-2482 (1997)).

[0110] Inhibitory Activity of Antagonists of Superactivated α_(v)β₃ Against other Integrins

[0111] If desired, antagonists of superactivated α_(v)β₃ are assayed for the ability to inhibit other integrins such as α_(v)β₅, α_(v)β₁ and α_(v)β₆ using cancer cell lines known to stably express high levels of these integrins. The human 293 embryonic kidney expresses α_(v)β₁ (Hu et al., J. Biol. Chem. 270:26232-26238 (1995)); SW480 colon adenocarcinoma cells express α_(v)β₆ (Agres et al., J. Cell Biol. 127:547-556 (1994)); available from Dr. R. Pytela); and U251 glioma cells express uV,5 (Deryugina et al., J. Cell Sci. 110:2473-2482 (1997) and Deryugina et al., Anticancer Res. 17:3201-3210 (1997)). The appropriate cells are plated on plastic coated with integrin-specific function-blocking antibodies (clone 6S6 for anti-β1; clone 10D5 for anti-α_(v)β₆ and clone P1F6 for α_(v)β₅ ; all clones are from Chemicon) and individual matrix proteins such as vitronectin, fibronectin, tenascin, collagen type I or IV at 0.1-10 βg/ml with and without the antagonists of superactivated α_(v)β₃. Function-blocking α_(v) specific L230 nab (ATCC) or LiAL mAb (Deryugina et al., Int. J. Cancer 86:15-23 (2000)) or RGD-peptides are used as controls. Adherent cells are counted as described above.

[0112] Use of Xenoaraph Models in Immuno-deficient Mice to Analyze Anti-tumoricfenic Activity of Antagonists of α_(v)β₃

[0113] In vivo anti-tumorigenic and anti-angiogenic effects of antagonists of superactivated α_(v)β₃ can be demonstrated as follows.

[0114] To evaluate tumor growth and metastatic potential, β3/MT1-MMP-MCF7 and MT1-MMP-U251.3 human glioma cells are injected into the mammary fat pads and in the tail vein of 6 week old female nu/nu mice, respectively (5×10⁶ cells per site; 5-8 mice/group). Tumors originating from MT1-MMP-U251.3 cells have previously been characterized as having very high growth rates and high levels of neovascularization relative to control cells. The use of transfected MT1-MMP-U251.3 glioma cells facilitates evaluation of in vivo anti-tumorigenic effects of antagonists of superactivated α_(v)β₃. These antagonists are administered i.p. 1, 3 and 10 mg/kg body weight daily for 6-8 weeks (four groups including control), and their effects on tumor growth, metastasis and neovascularization evaluated.

[0115] Tumor growth is monitored weekly by measuring mean diameter of the tumors. Size of the tumors is estimated as a volume of a sphere with the mean diameter of the tumor (mm³). At 6-8 weeks mice are sacrificed by cervical dislocation, and tumors are resected, weighed and dissected. For morphological and immunohistochemical analyses, tumor sections are frozen in liquid nitrogen or fixed.

[0116] To assess metastatic potential of cell transfectants, lungs and kidneys from the euthanized mice are examined for tumor nodules. Before euthanasia, Evans blue is injected intravenously, followed by vascular perfusion. Tumor growth in the mammary fat pads is evaluated weekly, and sections from resected tissues are analyzed by immunohistochemistry as described below.

[0117] Immunohistochemistry is performed as follows. Primary tumors and internal organs of interest (lungs, kidneys, liver) from nu/nu mice are resected and frozen or embedded in paraffin. Sections (5-6 mm thick) are prepared and stained with 10-20 mg/ml of MT1-MMP-, α_(v), α_(v)β₃-, β3- and MMP-2-specific antibodies, which are commercially available from Calbiochem, Chemicon International, Neomarkers and Amersham. Bound primary antibodies are detected with the appropriate secondary antibodies conjugated with HRP. Peroxidase activity in sections is developed with DAB. To measure levels of MMP-2 and MT1-MMP, resected tissues are extracted with 2% SDS, and the extracts analyzed by Western blotting and zymography. CD31 staining is used to verify levels of tumor angiogenesis.

[0118] MMP-2 activity is analyzed as follows. Since MT1-MMP initiates activation of MMP-2 and integrin α_(v)β₃ facilitates activation to the MMP-2's maturation (Deryugina et al., Int. J. Cancer 86:15-23 (2000)), MMP-2 activity is analyzed in gels co-polymerized with 0.1% gelatin. For these purposes, the core (most central) and periphery (adjacent to the capsule) portions of each tumor are extracted overnight with 2×SDS sample buffer (1:4, w/v) at room temperature. The extracts are mixed 1:1 with 60% glycerol, analyzed and processed by gelatin zymography as described in Deryugina et al., J. Cell Sci. 110:2473-2482 (1997).

[0119] Optimization of Antagonists of α_(v)β₃

[0120] Optimization of agonists and antagonists of superactivated α_(v)β₃ is performed as follows. A computerized search by using Chemix (Oxford Molecular Group, Oxford, UK) and ISIS (MDL Information Systems, San Leandro, Calif.) software is made in order to identify other 2-D and 3-D structurally related compounds in libraries such as ChemBridge libraries. Such structurally related molecules are screened for the ability to specifically inhibit superactivated α_(v)β₃, and optimized inhibitors are re-tested in vitro and in vivo. Further, cytotoxicity and the LD₅₀ value of optimized compounds is assessed by standard methods.

[0121] All journal article, reference, and patent citations provided above, in parentheses or otherwise, whether previously stated or not, are incorporated herein by reference.

[0122] Although the invention has been described with reference to the examples above, it should be understood that various modifications can be made without departing from the spirit of the invention. Accordingly, the invention is limited only by the following claims.

1 12 1 2367 DNA Homo sapiens CDS (1)...(2364) 1 atg cga gcg cgg ccg cgg ccc cgg ccg ctc tgg gtg act gtg ctg gcg 48 Met Arg Ala Arg Pro Arg Pro Arg Pro Leu Trp Val Thr Val Leu Ala 1 5 10 15 ctg ggg gcg ctg gcg ggc gtt ggc gta gga ggg ccc aac atc tgt acc 96 Leu Gly Ala Leu Ala Gly Val Gly Val Gly Gly Pro Asn Ile Cys Thr 20 25 30 acg cga ggt gtg agc tcc tgc cag cag tgc ctg gct gtg agc ccc atg 144 Thr Arg Gly Val Ser Ser Cys Gln Gln Cys Leu Ala Val Ser Pro Met 35 40 45 tgt gcc tgg tgc tct gat gag gcc ctg cct ctg ggc tca cct cgc tgt 192 Cys Ala Trp Cys Ser Asp Glu Ala Leu Pro Leu Gly Ser Pro Arg Cys 50 55 60 gac ctg aag gag aat ctg ctg aag gat aac tgt gcc cca gaa tcc atc 240 Asp Leu Lys Glu Asn Leu Leu Lys Asp Asn Cys Ala Pro Glu Ser Ile 65 70 75 80 gag ttc cca gtg agt gag gcc cga gta cta gag gac agg ccc ctc agc 288 Glu Phe Pro Val Ser Glu Ala Arg Val Leu Glu Asp Arg Pro Leu Ser 85 90 95 gac aag ggc tct gga gac agc tcc cag gtc act caa gtc agt ccc cag 336 Asp Lys Gly Ser Gly Asp Ser Ser Gln Val Thr Gln Val Ser Pro Gln 100 105 110 agg att gca ctc cgg ctc cgg cca gat gat tcg aag aat ttc tcc atc 384 Arg Ile Ala Leu Arg Leu Arg Pro Asp Asp Ser Lys Asn Phe Ser Ile 115 120 125 caa gtg cgg cag gtg gag gat tac cct gtg gac atc tac tac ttg atg 432 Gln Val Arg Gln Val Glu Asp Tyr Pro Val Asp Ile Tyr Tyr Leu Met 130 135 140 gac ctg tct tac tcc atg aag gat gat ctg tgg agc atc cag aac ctg 480 Asp Leu Ser Tyr Ser Met Lys Asp Asp Leu Trp Ser Ile Gln Asn Leu 145 150 155 160 ggt acc aag ctg gcc acc cag atg cga aag ctc acc agt aac ctg cgg 528 Gly Thr Lys Leu Ala Thr Gln Met Arg Lys Leu Thr Ser Asn Leu Arg 165 170 175 att ggc ttc ggg gca ttt gtg gac aag cct gtg tca cca tac atg tat 576 Ile Gly Phe Gly Ala Phe Val Asp Lys Pro Val Ser Pro Tyr Met Tyr 180 185 190 atc tcc cca cca gag gcc ctc gaa aac ccc tgc tat gat atg aag acc 624 Ile Ser Pro Pro Glu Ala Leu Glu Asn Pro Cys Tyr Asp Met Lys Thr 195 200 205 acc tgc ttg ccc atg ttt ggc tac aaa cac gtg ctg acg cta act gac 672 Thr Cys Leu Pro Met Phe Gly Tyr Lys His Val Leu Thr Leu Thr Asp 210 215 220 cag gtg acc cgc ttc aat gag gaa gtg aag aag cag agt gtg tca cgg 720 Gln Val Thr Arg Phe Asn Glu Glu Val Lys Lys Gln Ser Val Ser Arg 225 230 235 240 aac cga gat gcc cca gag ggt ggc ttt gat gcc atc atg cag gct aca 768 Asn Arg Asp Ala Pro Glu Gly Gly Phe Asp Ala Ile Met Gln Ala Thr 245 250 255 gtc tgt gat gaa aag att ggc tgg agg aat gat gca tcc cac ttg ctg 816 Val Cys Asp Glu Lys Ile Gly Trp Arg Asn Asp Ala Ser His Leu Leu 260 265 270 gtg ttt acc act gat gcc aag act cat ata gca ttg gac gga agg ctg 864 Val Phe Thr Thr Asp Ala Lys Thr His Ile Ala Leu Asp Gly Arg Leu 275 280 285 gca ggc att gtc cag cct aat gac ggg cag tgt cat gtt ggt agt gac 912 Ala Gly Ile Val Gln Pro Asn Asp Gly Gln Cys His Val Gly Ser Asp 290 295 300 aat cat tac tct gcc tcc act acc atg gat tat ccc tct ttg ggg ctg 960 Asn His Tyr Ser Ala Ser Thr Thr Met Asp Tyr Pro Ser Leu Gly Leu 305 310 315 320 atg act gag aag cta tcc cag aaa aac atc aat ttg atc ttt gca gtg 1008 Met Thr Glu Lys Leu Ser Gln Lys Asn Ile Asn Leu Ile Phe Ala Val 325 330 335 act gaa aat gta gtc aat ctc tat cag aac tat agt gag ctc atc cca 1056 Thr Glu Asn Val Val Asn Leu Tyr Gln Asn Tyr Ser Glu Leu Ile Pro 340 345 350 ggg acc aca gtt ggg gtt ctg tcc atg gat tcc agc aat gtc ctc cag 1104 Gly Thr Thr Val Gly Val Leu Ser Met Asp Ser Ser Asn Val Leu Gln 355 360 365 ctc att gtt gat gct tat ggg aaa atc cgt tct aaa gtc gag ctg gaa 1152 Leu Ile Val Asp Ala Tyr Gly Lys Ile Arg Ser Lys Val Glu Leu Glu 370 375 380 gtg cgt gac ctc cct gaa gag ttg tct cta tcc ttc aat gcc acc tgc 1200 Val Arg Asp Leu Pro Glu Glu Leu Ser Leu Ser Phe Asn Ala Thr Cys 385 390 395 400 ctc aac aat gag gtc atc cct ggc ctc aag tct tgt atg gga ctc aag 1248 Leu Asn Asn Glu Val Ile Pro Gly Leu Lys Ser Cys Met Gly Leu Lys 405 410 415 att gga gac acg gtg agc ttc agc att gag gcc aag gtg cga ggc tgt 1296 Ile Gly Asp Thr Val Ser Phe Ser Ile Glu Ala Lys Val Arg Gly Cys 420 425 430 ccc cag gag aag gag aag tcc ttt acc ata aag ccc gtg ggc ttc aag 1344 Pro Gln Glu Lys Glu Lys Ser Phe Thr Ile Lys Pro Val Gly Phe Lys 435 440 445 gac agc ctg atc gtc cag gtc acc ttt gat tgt gac tgt gcc tgc cag 1392 Asp Ser Leu Ile Val Gln Val Thr Phe Asp Cys Asp Cys Ala Cys Gln 450 455 460 gcc caa gct gaa cct aat agc cat cgc tgc aac aat ggc aat ggg acc 1440 Ala Gln Ala Glu Pro Asn Ser His Arg Cys Asn Asn Gly Asn Gly Thr 465 470 475 480 ttt gag tgt ggg gta tgc cgt tgt ggg cct ggc tgg ctg gga tcc cag 1488 Phe Glu Cys Gly Val Cys Arg Cys Gly Pro Gly Trp Leu Gly Ser Gln 485 490 495 tgt gag tgc tca gag gag gac tat cgc cct tcc cag cag gac gag tgc 1536 Cys Glu Cys Ser Glu Glu Asp Tyr Arg Pro Ser Gln Gln Asp Glu Cys 500 505 510 agc ccc cga gag ggt cag ccc gtc tgc agc cag cgg ggc gag tgc ctc 1584 Ser Pro Arg Glu Gly Gln Pro Val Cys Ser Gln Arg Gly Glu Cys Leu 515 520 525 tgt ggt caa tgt gtc tgc cac agc agt gac ttt ggc aag atc acg ggc 1632 Cys Gly Gln Cys Val Cys His Ser Ser Asp Phe Gly Lys Ile Thr Gly 530 535 540 aag tac tgc gag tgt gac gac ttc tcc tgt gtc cgc tac aag ggg gag 1680 Lys Tyr Cys Glu Cys Asp Asp Phe Ser Cys Val Arg Tyr Lys Gly Glu 545 550 555 560 atg tgc tca ggc cat ggc cag tgc agc tgt ggg gac tgc ctg tgt gac 1728 Met Cys Ser Gly His Gly Gln Cys Ser Cys Gly Asp Cys Leu Cys Asp 565 570 575 tcc gac tgg acc ggc tac tac tgc aac tgt acc acg cgt act gac acc 1776 Ser Asp Trp Thr Gly Tyr Tyr Cys Asn Cys Thr Thr Arg Thr Asp Thr 580 585 590 tgc atg tcc agc aat ggg ctg ctg tgc agc ggc cgc ggc aag tgt gaa 1824 Cys Met Ser Ser Asn Gly Leu Leu Cys Ser Gly Arg Gly Lys Cys Glu 595 600 605 tgt ggc agc tgt gtc tgt atc cag ccg ggc tcc tat ggg gac acc tgt 1872 Cys Gly Ser Cys Val Cys Ile Gln Pro Gly Ser Tyr Gly Asp Thr Cys 610 615 620 gag aag tgc ccc acc tgc cca gat gcc tgc acc ttt aag aaa gaa tgt 1920 Glu Lys Cys Pro Thr Cys Pro Asp Ala Cys Thr Phe Lys Lys Glu Cys 625 630 635 640 gtg gag tgt aag aag ttt gac cgg gag ccc tac atg acc gaa aat acc 1968 Val Glu Cys Lys Lys Phe Asp Arg Glu Pro Tyr Met Thr Glu Asn Thr 645 650 655 tgc aac cgt tac tgc cgt gac gag att gag tca gtg aaa gag ctt aag 2016 Cys Asn Arg Tyr Cys Arg Asp Glu Ile Glu Ser Val Lys Glu Leu Lys 660 665 670 gac act ggc aag gat gca gtg aat tgt acc tat aag aat gag gat gac 2064 Asp Thr Gly Lys Asp Ala Val Asn Cys Thr Tyr Lys Asn Glu Asp Asp 675 680 685 tgt gtc gtc aga ttc cag tac tat gaa gat tct agt gga aag tcc atc 2112 Cys Val Val Arg Phe Gln Tyr Tyr Glu Asp Ser Ser Gly Lys Ser Ile 690 695 700 ctg tat gtg gta gaa gag cca gag tgt ccc aag ggc cct gac atc ctg 2160 Leu Tyr Val Val Glu Glu Pro Glu Cys Pro Lys Gly Pro Asp Ile Leu 705 710 715 720 gtg gtc ctg ctc tca gtg atg ggg gcc att ctg ctc att ggc ctt gcc 2208 Val Val Leu Leu Ser Val Met Gly Ala Ile Leu Leu Ile Gly Leu Ala 725 730 735 gcc ctg ctc atc tgg aaa ctc ctc atc acc atc cac gac cga aaa gaa 2256 Ala Leu Leu Ile Trp Lys Leu Leu Ile Thr Ile His Asp Arg Lys Glu 740 745 750 ttc gct aaa ttt gag gaa gaa cgc gcc aga gca aaa tgg gac aca gcc 2304 Phe Ala Lys Phe Glu Glu Glu Arg Ala Arg Ala Lys Trp Asp Thr Ala 755 760 765 aac aac cca ctg tat aaa gag gcc acg tct acc ttc acc aat atc acg 2352 Asn Asn Pro Leu Tyr Lys Glu Ala Thr Ser Thr Phe Thr Asn Ile Thr 770 775 780 tac cgg ggc act taa 2367 Tyr Arg Gly Thr 785 2 788 PRT Homo sapiens 2 Met Arg Ala Arg Pro Arg Pro Arg Pro Leu Trp Val Thr Val Leu Ala 1 5 10 15 Leu Gly Ala Leu Ala Gly Val Gly Val Gly Gly Pro Asn Ile Cys Thr 20 25 30 Thr Arg Gly Val Ser Ser Cys Gln Gln Cys Leu Ala Val Ser Pro Met 35 40 45 Cys Ala Trp Cys Ser Asp Glu Ala Leu Pro Leu Gly Ser Pro Arg Cys 50 55 60 Asp Leu Lys Glu Asn Leu Leu Lys Asp Asn Cys Ala Pro Glu Ser Ile 65 70 75 80 Glu Phe Pro Val Ser Glu Ala Arg Val Leu Glu Asp Arg Pro Leu Ser 85 90 95 Asp Lys Gly Ser Gly Asp Ser Ser Gln Val Thr Gln Val Ser Pro Gln 100 105 110 Arg Ile Ala Leu Arg Leu Arg Pro Asp Asp Ser Lys Asn Phe Ser Ile 115 120 125 Gln Val Arg Gln Val Glu Asp Tyr Pro Val Asp Ile Tyr Tyr Leu Met 130 135 140 Asp Leu Ser Tyr Ser Met Lys Asp Asp Leu Trp Ser Ile Gln Asn Leu 145 150 155 160 Gly Thr Lys Leu Ala Thr Gln Met Arg Lys Leu Thr Ser Asn Leu Arg 165 170 175 Ile Gly Phe Gly Ala Phe Val Asp Lys Pro Val Ser Pro Tyr Met Tyr 180 185 190 Ile Ser Pro Pro Glu Ala Leu Glu Asn Pro Cys Tyr Asp Met Lys Thr 195 200 205 Thr Cys Leu Pro Met Phe Gly Tyr Lys His Val Leu Thr Leu Thr Asp 210 215 220 Gln Val Thr Arg Phe Asn Glu Glu Val Lys Lys Gln Ser Val Ser Arg 225 230 235 240 Asn Arg Asp Ala Pro Glu Gly Gly Phe Asp Ala Ile Met Gln Ala Thr 245 250 255 Val Cys Asp Glu Lys Ile Gly Trp Arg Asn Asp Ala Ser His Leu Leu 260 265 270 Val Phe Thr Thr Asp Ala Lys Thr His Ile Ala Leu Asp Gly Arg Leu 275 280 285 Ala Gly Ile Val Gln Pro Asn Asp Gly Gln Cys His Val Gly Ser Asp 290 295 300 Asn His Tyr Ser Ala Ser Thr Thr Met Asp Tyr Pro Ser Leu Gly Leu 305 310 315 320 Met Thr Glu Lys Leu Ser Gln Lys Asn Ile Asn Leu Ile Phe Ala Val 325 330 335 Thr Glu Asn Val Val Asn Leu Tyr Gln Asn Tyr Ser Glu Leu Ile Pro 340 345 350 Gly Thr Thr Val Gly Val Leu Ser Met Asp Ser Ser Asn Val Leu Gln 355 360 365 Leu Ile Val Asp Ala Tyr Gly Lys Ile Arg Ser Lys Val Glu Leu Glu 370 375 380 Val Arg Asp Leu Pro Glu Glu Leu Ser Leu Ser Phe Asn Ala Thr Cys 385 390 395 400 Leu Asn Asn Glu Val Ile Pro Gly Leu Lys Ser Cys Met Gly Leu Lys 405 410 415 Ile Gly Asp Thr Val Ser Phe Ser Ile Glu Ala Lys Val Arg Gly Cys 420 425 430 Pro Gln Glu Lys Glu Lys Ser Phe Thr Ile Lys Pro Val Gly Phe Lys 435 440 445 Asp Ser Leu Ile Val Gln Val Thr Phe Asp Cys Asp Cys Ala Cys Gln 450 455 460 Ala Gln Ala Glu Pro Asn Ser His Arg Cys Asn Asn Gly Asn Gly Thr 465 470 475 480 Phe Glu Cys Gly Val Cys Arg Cys Gly Pro Gly Trp Leu Gly Ser Gln 485 490 495 Cys Glu Cys Ser Glu Glu Asp Tyr Arg Pro Ser Gln Gln Asp Glu Cys 500 505 510 Ser Pro Arg Glu Gly Gln Pro Val Cys Ser Gln Arg Gly Glu Cys Leu 515 520 525 Cys Gly Gln Cys Val Cys His Ser Ser Asp Phe Gly Lys Ile Thr Gly 530 535 540 Lys Tyr Cys Glu Cys Asp Asp Phe Ser Cys Val Arg Tyr Lys Gly Glu 545 550 555 560 Met Cys Ser Gly His Gly Gln Cys Ser Cys Gly Asp Cys Leu Cys Asp 565 570 575 Ser Asp Trp Thr Gly Tyr Tyr Cys Asn Cys Thr Thr Arg Thr Asp Thr 580 585 590 Cys Met Ser Ser Asn Gly Leu Leu Cys Ser Gly Arg Gly Lys Cys Glu 595 600 605 Cys Gly Ser Cys Val Cys Ile Gln Pro Gly Ser Tyr Gly Asp Thr Cys 610 615 620 Glu Lys Cys Pro Thr Cys Pro Asp Ala Cys Thr Phe Lys Lys Glu Cys 625 630 635 640 Val Glu Cys Lys Lys Phe Asp Arg Glu Pro Tyr Met Thr Glu Asn Thr 645 650 655 Cys Asn Arg Tyr Cys Arg Asp Glu Ile Glu Ser Val Lys Glu Leu Lys 660 665 670 Asp Thr Gly Lys Asp Ala Val Asn Cys Thr Tyr Lys Asn Glu Asp Asp 675 680 685 Cys Val Val Arg Phe Gln Tyr Tyr Glu Asp Ser Ser Gly Lys Ser Ile 690 695 700 Leu Tyr Val Val Glu Glu Pro Glu Cys Pro Lys Gly Pro Asp Ile Leu 705 710 715 720 Val Val Leu Leu Ser Val Met Gly Ala Ile Leu Leu Ile Gly Leu Ala 725 730 735 Ala Leu Leu Ile Trp Lys Leu Leu Ile Thr Ile His Asp Arg Lys Glu 740 745 750 Phe Ala Lys Phe Glu Glu Glu Arg Ala Arg Ala Lys Trp Asp Thr Ala 755 760 765 Asn Asn Pro Leu Tyr Lys Glu Ala Thr Ser Thr Phe Thr Asn Ile Thr 770 775 780 Tyr Arg Gly Thr 785 3 1749 DNA Homo sapiens CDS (1)...(1746) 3 atg tct ccc gcc cca aga ccc ccc cgt tgt ctc ctg ctc ccc ctg ctc 48 Met Ser Pro Ala Pro Arg Pro Pro Arg Cys Leu Leu Leu Pro Leu Leu 1 5 10 15 acg ctc ggc acc gcg ctc gcc tcc ctc ggc tcg gcc caa agc agc agc 96 Thr Leu Gly Thr Ala Leu Ala Ser Leu Gly Ser Ala Gln Ser Ser Ser 20 25 30 ttc agc ccc gaa gcc tgg cta cag caa tat ggc tac ctg cct ccc ggg 144 Phe Ser Pro Glu Ala Trp Leu Gln Gln Tyr Gly Tyr Leu Pro Pro Gly 35 40 45 gac cta cgt acc cac aca cag cgc tca ccc cag tca ctc tca gcg gcc 192 Asp Leu Arg Thr His Thr Gln Arg Ser Pro Gln Ser Leu Ser Ala Ala 50 55 60 atc gct gcc atg cag aag ttt tac ggc ttg caa gta aca ggc aaa gct 240 Ile Ala Ala Met Gln Lys Phe Tyr Gly Leu Gln Val Thr Gly Lys Ala 65 70 75 80 gat gca gac acc atg aag gcc atg agg cgc ccc cga tgt ggt gtt cca 288 Asp Ala Asp Thr Met Lys Ala Met Arg Arg Pro Arg Cys Gly Val Pro 85 90 95 gac aag ttt ggg gct gag atc aag gcc aat gtt cga agg aag cgc tac 336 Asp Lys Phe Gly Ala Glu Ile Lys Ala Asn Val Arg Arg Lys Arg Tyr 100 105 110 gcc atc cag ggt ctc aaa tgg caa cat aat gaa atc act ttc tgc atc 384 Ala Ile Gln Gly Leu Lys Trp Gln His Asn Glu Ile Thr Phe Cys Ile 115 120 125 cag aat tac acc ccc aag gtg ggc gag tat gcc aca tac gag gcc att 432 Gln Asn Tyr Thr Pro Lys Val Gly Glu Tyr Ala Thr Tyr Glu Ala Ile 130 135 140 cgc aag gcg ttc cgc gtg tgg gag agt gcc aca cca ctg cgc ttc cgc 480 Arg Lys Ala Phe Arg Val Trp Glu Ser Ala Thr Pro Leu Arg Phe Arg 145 150 155 160 gag gtg ccc tat gcc tac atc cgt gag ggc cat gag aag cag gcc gac 528 Glu Val Pro Tyr Ala Tyr Ile Arg Glu Gly His Glu Lys Gln Ala Asp 165 170 175 atc atg atc ttc ttt gcc gag ggc ttc cat ggc gac agc acg ccc ttc 576 Ile Met Ile Phe Phe Ala Glu Gly Phe His Gly Asp Ser Thr Pro Phe 180 185 190 gat ggt gag ggc ggc ttc ctg gcc cat gcc tac ttc cca ggc ccc aac 624 Asp Gly Glu Gly Gly Phe Leu Ala His Ala Tyr Phe Pro Gly Pro Asn 195 200 205 att gga gga gac acc cac ttt gac tct gcc gag cct tgg act gtc agg 672 Ile Gly Gly Asp Thr His Phe Asp Ser Ala Glu Pro Trp Thr Val Arg 210 215 220 aat gag gat ctg aat gga aat gac atc ttc ctg gtg gct gtg cac gag 720 Asn Glu Asp Leu Asn Gly Asn Asp Ile Phe Leu Val Ala Val His Glu 225 230 235 240 ctg ggc cat gcc ctg ggg ctc gag cat tcc agt gac ccc tcg gcc atc 768 Leu Gly His Ala Leu Gly Leu Glu His Ser Ser Asp Pro Ser Ala Ile 245 250 255 atg gca ccc ttt tac cag tgg atg gac acg gag aat ttt gtg ctg ccc 816 Met Ala Pro Phe Tyr Gln Trp Met Asp Thr Glu Asn Phe Val Leu Pro 260 265 270 gat gat gac cgc cgg ggc atc cag caa ctt tat ggg ggt gag tca ggg 864 Asp Asp Asp Arg Arg Gly Ile Gln Gln Leu Tyr Gly Gly Glu Ser Gly 275 280 285 ttc ccc acc aag atg ccc cct caa ccc agg act acc tcc cgg cct tct 912 Phe Pro Thr Lys Met Pro Pro Gln Pro Arg Thr Thr Ser Arg Pro Ser 290 295 300 gtt cct gat aaa ccc aaa aac ccc acc tat ggg ccc aac atc tgt gac 960 Val Pro Asp Lys Pro Lys Asn Pro Thr Tyr Gly Pro Asn Ile Cys Asp 305 310 315 320 ggg aac ttt gac acc gtg gcc atg ctc cga ggg gag atg ttt gtc ttc 1008 Gly Asn Phe Asp Thr Val Ala Met Leu Arg Gly Glu Met Phe Val Phe 325 330 335 aag gag cgc tgg ttc tgg cgg gtg agg aat aac caa gtg atg gat gga 1056 Lys Glu Arg Trp Phe Trp Arg Val Arg Asn Asn Gln Val Met Asp Gly 340 345 350 tac cca atg ccc att ggc cag ttc tgg cgg ggc ctg cct gcg tcc atc 1104 Tyr Pro Met Pro Ile Gly Gln Phe Trp Arg Gly Leu Pro Ala Ser Ile 355 360 365 aac act gcc tac gag agg aag gat ggc aaa ttc gtc ttc ttc aaa gga 1152 Asn Thr Ala Tyr Glu Arg Lys Asp Gly Lys Phe Val Phe Phe Lys Gly 370 375 380 gac aag cat tgg gtg ttt gat gag gcg tcc ctg gaa cct ggc tac ccc 1200 Asp Lys His Trp Val Phe Asp Glu Ala Ser Leu Glu Pro Gly Tyr Pro 385 390 395 400 aag cac att aag gag ctg ggc cga ggg ctg cct acc gac aag att gat 1248 Lys His Ile Lys Glu Leu Gly Arg Gly Leu Pro Thr Asp Lys Ile Asp 405 410 415 gct gct ctc ttc tgg atg ccc aat gga aag acc tac ttc ttc cgt gga 1296 Ala Ala Leu Phe Trp Met Pro Asn Gly Lys Thr Tyr Phe Phe Arg Gly 420 425 430 aac aag tac tac cgt ttc aac gaa gag ctc agg gca gtg gat agc gag 1344 Asn Lys Tyr Tyr Arg Phe Asn Glu Glu Leu Arg Ala Val Asp Ser Glu 435 440 445 tac ccc aag aac atc aaa gtc tgg gaa ggg atc cct gag tct ccc aga 1392 Tyr Pro Lys Asn Ile Lys Val Trp Glu Gly Ile Pro Glu Ser Pro Arg 450 455 460 ggg tca ttc atg ggc agc gat gaa gtc ttc act tac ttc tac aag ggg 1440 Gly Ser Phe Met Gly Ser Asp Glu Val Phe Thr Tyr Phe Tyr Lys Gly 465 470 475 480 aac aaa tac tgg aaa ttc aac aac cag aag ctg aag gta gaa ccg ggc 1488 Asn Lys Tyr Trp Lys Phe Asn Asn Gln Lys Leu Lys Val Glu Pro Gly 485 490 495 tac ccc aag tca gcc ctg agg gac tgg atg ggc tgc cca tcg gga ggc 1536 Tyr Pro Lys Ser Ala Leu Arg Asp Trp Met Gly Cys Pro Ser Gly Gly 500 505 510 cgg ccg gat gag ggg act gag gag gag acg gag gtg atc atc att gag 1584 Arg Pro Asp Glu Gly Thr Glu Glu Glu Thr Glu Val Ile Ile Ile Glu 515 520 525 gtg gac gag gag ggc ggc ggg gcg gtg agc gcg gct gcc gtg gtg ctg 1632 Val Asp Glu Glu Gly Gly Gly Ala Val Ser Ala Ala Ala Val Val Leu 530 535 540 ccc gtg ctg ctg ctg ctc ctg gtg ctg gcg gtg ggc ctt gca gtc ttc 1680 Pro Val Leu Leu Leu Leu Leu Val Leu Ala Val Gly Leu Ala Val Phe 545 550 555 560 ttc ttc aga cgc cat ggg acc ccc agg cga ctg ctc tac tgc cag cgt 1728 Phe Phe Arg Arg His Gly Thr Pro Arg Arg Leu Leu Tyr Cys Gln Arg 565 570 575 tcc ctg ctg gac aag gtc tga 1749 Ser Leu Leu Asp Lys Val 580 4 582 PRT Homo sapiens 4 Met Ser Pro Ala Pro Arg Pro Pro Arg Cys Leu Leu Leu Pro Leu Leu 1 5 10 15 Thr Leu Gly Thr Ala Leu Ala Ser Leu Gly Ser Ala Gln Ser Ser Ser 20 25 30 Phe Ser Pro Glu Ala Trp Leu Gln Gln Tyr Gly Tyr Leu Pro Pro Gly 35 40 45 Asp Leu Arg Thr His Thr Gln Arg Ser Pro Gln Ser Leu Ser Ala Ala 50 55 60 Ile Ala Ala Met Gln Lys Phe Tyr Gly Leu Gln Val Thr Gly Lys Ala 65 70 75 80 Asp Ala Asp Thr Met Lys Ala Met Arg Arg Pro Arg Cys Gly Val Pro 85 90 95 Asp Lys Phe Gly Ala Glu Ile Lys Ala Asn Val Arg Arg Lys Arg Tyr 100 105 110 Ala Ile Gln Gly Leu Lys Trp Gln His Asn Glu Ile Thr Phe Cys Ile 115 120 125 Gln Asn Tyr Thr Pro Lys Val Gly Glu Tyr Ala Thr Tyr Glu Ala Ile 130 135 140 Arg Lys Ala Phe Arg Val Trp Glu Ser Ala Thr Pro Leu Arg Phe Arg 145 150 155 160 Glu Val Pro Tyr Ala Tyr Ile Arg Glu Gly His Glu Lys Gln Ala Asp 165 170 175 Ile Met Ile Phe Phe Ala Glu Gly Phe His Gly Asp Ser Thr Pro Phe 180 185 190 Asp Gly Glu Gly Gly Phe Leu Ala His Ala Tyr Phe Pro Gly Pro Asn 195 200 205 Ile Gly Gly Asp Thr His Phe Asp Ser Ala Glu Pro Trp Thr Val Arg 210 215 220 Asn Glu Asp Leu Asn Gly Asn Asp Ile Phe Leu Val Ala Val His Glu 225 230 235 240 Leu Gly His Ala Leu Gly Leu Glu His Ser Ser Asp Pro Ser Ala Ile 245 250 255 Met Ala Pro Phe Tyr Gln Trp Met Asp Thr Glu Asn Phe Val Leu Pro 260 265 270 Asp Asp Asp Arg Arg Gly Ile Gln Gln Leu Tyr Gly Gly Glu Ser Gly 275 280 285 Phe Pro Thr Lys Met Pro Pro Gln Pro Arg Thr Thr Ser Arg Pro Ser 290 295 300 Val Pro Asp Lys Pro Lys Asn Pro Thr Tyr Gly Pro Asn Ile Cys Asp 305 310 315 320 Gly Asn Phe Asp Thr Val Ala Met Leu Arg Gly Glu Met Phe Val Phe 325 330 335 Lys Glu Arg Trp Phe Trp Arg Val Arg Asn Asn Gln Val Met Asp Gly 340 345 350 Tyr Pro Met Pro Ile Gly Gln Phe Trp Arg Gly Leu Pro Ala Ser Ile 355 360 365 Asn Thr Ala Tyr Glu Arg Lys Asp Gly Lys Phe Val Phe Phe Lys Gly 370 375 380 Asp Lys His Trp Val Phe Asp Glu Ala Ser Leu Glu Pro Gly Tyr Pro 385 390 395 400 Lys His Ile Lys Glu Leu Gly Arg Gly Leu Pro Thr Asp Lys Ile Asp 405 410 415 Ala Ala Leu Phe Trp Met Pro Asn Gly Lys Thr Tyr Phe Phe Arg Gly 420 425 430 Asn Lys Tyr Tyr Arg Phe Asn Glu Glu Leu Arg Ala Val Asp Ser Glu 435 440 445 Tyr Pro Lys Asn Ile Lys Val Trp Glu Gly Ile Pro Glu Ser Pro Arg 450 455 460 Gly Ser Phe Met Gly Ser Asp Glu Val Phe Thr Tyr Phe Tyr Lys Gly 465 470 475 480 Asn Lys Tyr Trp Lys Phe Asn Asn Gln Lys Leu Lys Val Glu Pro Gly 485 490 495 Tyr Pro Lys Ser Ala Leu Arg Asp Trp Met Gly Cys Pro Ser Gly Gly 500 505 510 Arg Pro Asp Glu Gly Thr Glu Glu Glu Thr Glu Val Ile Ile Ile Glu 515 520 525 Val Asp Glu Glu Gly Gly Gly Ala Val Ser Ala Ala Ala Val Val Leu 530 535 540 Pro Val Leu Leu Leu Leu Leu Val Leu Ala Val Gly Leu Ala Val Phe 545 550 555 560 Phe Phe Arg Arg His Gly Thr Pro Arg Arg Leu Leu Tyr Cys Gln Arg 565 570 575 Ser Leu Leu Asp Lys Val 580 5 2367 DNA Homo sapiens CDS (1)...(2364) 5 atg cga gcg cgg ccg cgg ccc cgg ccg ctc tgg gtg act gtg ctg gcg 48 Met Arg Ala Arg Pro Arg Pro Arg Pro Leu Trp Val Thr Val Leu Ala 1 5 10 15 ctg ggg gcg ctg gcg ggc gtt ggc gta gga ggg ccc aac atc tgt acc 96 Leu Gly Ala Leu Ala Gly Val Gly Val Gly Gly Pro Asn Ile Cys Thr 20 25 30 acg cga ggt gtg agc tcc tgc cag cag tgc ctg gct gtg agc ccc atg 144 Thr Arg Gly Val Ser Ser Cys Gln Gln Cys Leu Ala Val Ser Pro Met 35 40 45 tgt gcc tgg tgc tct gat gag gcc ctg cct ctg ggc tca cct cgc tgt 192 Cys Ala Trp Cys Ser Asp Glu Ala Leu Pro Leu Gly Ser Pro Arg Cys 50 55 60 gac ctg aag gag act cag ctg aag gat aac tgt gcc cca gaa tcc atc 240 Asp Leu Lys Glu Thr Gln Leu Lys Asp Asn Cys Ala Pro Glu Ser Ile 65 70 75 80 gag ttc cca gtg agt gag gcc cga gta cta gag gac agg ccc ctc agc 288 Glu Phe Pro Val Ser Glu Ala Arg Val Leu Glu Asp Arg Pro Leu Ser 85 90 95 gac aag ggc tct gga gac agc tcc cag gtc act caa gtc agt ccc cag 336 Asp Lys Gly Ser Gly Asp Ser Ser Gln Val Thr Gln Val Ser Pro Gln 100 105 110 agg att gca ctc cgg ctc cgg cca gat gat tcg aag aat ttc tcc atc 384 Arg Ile Ala Leu Arg Leu Arg Pro Asp Asp Ser Lys Asn Phe Ser Ile 115 120 125 caa gtg cgg cag gtg gag gat tac cct gtg gac atc tac tac ttg atg 432 Gln Val Arg Gln Val Glu Asp Tyr Pro Val Asp Ile Tyr Tyr Leu Met 130 135 140 gac ctg tct tac tcc atg aag gat gat ctg tgg agc atc cag aac ctg 480 Asp Leu Ser Tyr Ser Met Lys Asp Asp Leu Trp Ser Ile Gln Asn Leu 145 150 155 160 ggt acc aag ctg gcc acc cag atg cga aag ctc acc agt aac ctg cgg 528 Gly Thr Lys Leu Ala Thr Gln Met Arg Lys Leu Thr Ser Asn Leu Arg 165 170 175 att ggc ttc ggg gca ttt gtg gac aag cct gtg tca cca tac atg tat 576 Ile Gly Phe Gly Ala Phe Val Asp Lys Pro Val Ser Pro Tyr Met Tyr 180 185 190 atc tcc cca cca gag gcc ctc gaa aac ccc tgc tat gat atg aag acc 624 Ile Ser Pro Pro Glu Ala Leu Glu Asn Pro Cys Tyr Asp Met Lys Thr 195 200 205 acc tgc ttg ccc atg ttt ggc tac aaa cac gtg ctg acg cta act gac 672 Thr Cys Leu Pro Met Phe Gly Tyr Lys His Val Leu Thr Leu Thr Asp 210 215 220 cag gtg acc cgc ttc aat gag gaa gtg aag aag cag agt gtg tca cgg 720 Gln Val Thr Arg Phe Asn Glu Glu Val Lys Lys Gln Ser Val Ser Arg 225 230 235 240 aac cga gat gcc cca gag ggt ggc ttt gat gcc atc atg cag gct aca 768 Asn Arg Asp Ala Pro Glu Gly Gly Phe Asp Ala Ile Met Gln Ala Thr 245 250 255 gtc tgt gat gaa aag att ggc tgg agg aat gat gca tcc cac ttg ctg 816 Val Cys Asp Glu Lys Ile Gly Trp Arg Asn Asp Ala Ser His Leu Leu 260 265 270 gtg ttt acc act gat gcc aag act cat ata gca ttg gac gga agg ctg 864 Val Phe Thr Thr Asp Ala Lys Thr His Ile Ala Leu Asp Gly Arg Leu 275 280 285 gca ggc att gtc cag cct aat gac ggg cag tgt cat gtt ggt agt gac 912 Ala Gly Ile Val Gln Pro Asn Asp Gly Gln Cys His Val Gly Ser Asp 290 295 300 aat cat tac tct gcc tcc act acc atg gat tat ccc tct ttg ggg ctg 960 Asn His Tyr Ser Ala Ser Thr Thr Met Asp Tyr Pro Ser Leu Gly Leu 305 310 315 320 atg act gag aag cta tcc cag aaa aac atc aat ttg atc ttt gca gtg 1008 Met Thr Glu Lys Leu Ser Gln Lys Asn Ile Asn Leu Ile Phe Ala Val 325 330 335 act gaa aat gta gtc aat ctc tat cag aac tat agt gag ctc atc cca 1056 Thr Glu Asn Val Val Asn Leu Tyr Gln Asn Tyr Ser Glu Leu Ile Pro 340 345 350 ggg acc aca gtt ggg gtt ctg tcc atg gat tcc agc aat gtc ctc cag 1104 Gly Thr Thr Val Gly Val Leu Ser Met Asp Ser Ser Asn Val Leu Gln 355 360 365 ctc att gtt gat gct tat ggg aaa atc cgt tct aaa gtc gag ctg gaa 1152 Leu Ile Val Asp Ala Tyr Gly Lys Ile Arg Ser Lys Val Glu Leu Glu 370 375 380 gtg cgt gac ctc cct gaa gag ttg tct cta tcc ttc aat gcc acc tgc 1200 Val Arg Asp Leu Pro Glu Glu Leu Ser Leu Ser Phe Asn Ala Thr Cys 385 390 395 400 ctc aac aat gag gtc atc cct ggc ctc aag tct tgt atg gga ctc aag 1248 Leu Asn Asn Glu Val Ile Pro Gly Leu Lys Ser Cys Met Gly Leu Lys 405 410 415 att gga gac acg gtg agc ttc agc att gag gcc aag gtg cga ggc tgt 1296 Ile Gly Asp Thr Val Ser Phe Ser Ile Glu Ala Lys Val Arg Gly Cys 420 425 430 ccc cag gag aag gag aag tcc ttt acc ata aag ccc gtg ggc ttc aag 1344 Pro Gln Glu Lys Glu Lys Ser Phe Thr Ile Lys Pro Val Gly Phe Lys 435 440 445 gac agc ctg atc gtc cag gtc acc ttt gat tgt gac tgt gcc tgc cag 1392 Asp Ser Leu Ile Val Gln Val Thr Phe Asp Cys Asp Cys Ala Cys Gln 450 455 460 gcc caa gct gaa cct aat agc cat cgc tgc aac aat ggc aat ggg acc 1440 Ala Gln Ala Glu Pro Asn Ser His Arg Cys Asn Asn Gly Asn Gly Thr 465 470 475 480 ttt gag tgt ggg gta tgc cgt tgt ggg cct ggc tgg ctg gga tcc cag 1488 Phe Glu Cys Gly Val Cys Arg Cys Gly Pro Gly Trp Leu Gly Ser Gln 485 490 495 tgt gag tgc tca gag gag gac tat cgc cct tcc cag cag gac gag tgc 1536 Cys Glu Cys Ser Glu Glu Asp Tyr Arg Pro Ser Gln Gln Asp Glu Cys 500 505 510 agc ccc cga gag ggt cag ccc gtc tgc agc cag cgg ggc gag tgc ctc 1584 Ser Pro Arg Glu Gly Gln Pro Val Cys Ser Gln Arg Gly Glu Cys Leu 515 520 525 tgt ggt caa tgt gtc tgc cac agc agt gac ttt ggc aag atc acg ggc 1632 Cys Gly Gln Cys Val Cys His Ser Ser Asp Phe Gly Lys Ile Thr Gly 530 535 540 aag tac tgc gag tgt gac gac ttc tcc tgt gtc cgc tac aag ggg gag 1680 Lys Tyr Cys Glu Cys Asp Asp Phe Ser Cys Val Arg Tyr Lys Gly Glu 545 550 555 560 atg tgc tca ggc cat ggc cag tgc agc tgt ggg gac tgc ctg tgt gac 1728 Met Cys Ser Gly His Gly Gln Cys Ser Cys Gly Asp Cys Leu Cys Asp 565 570 575 tcc gac tgg acc ggc tac tac tgc aac tgt acc acg cgt act gac acc 1776 Ser Asp Trp Thr Gly Tyr Tyr Cys Asn Cys Thr Thr Arg Thr Asp Thr 580 585 590 tgc atg tcc agc aat ggg ctg ctg tgc agc ggc cgc ggc aag tgt gaa 1824 Cys Met Ser Ser Asn Gly Leu Leu Cys Ser Gly Arg Gly Lys Cys Glu 595 600 605 tgt ggc agc tgt gtc tgt atc cag ccg ggc tcc tat ggg gac acc tgt 1872 Cys Gly Ser Cys Val Cys Ile Gln Pro Gly Ser Tyr Gly Asp Thr Cys 610 615 620 gag aag tgc ccc acc tgc cca gat gcc tgc acc ttt aag aaa gaa tgt 1920 Glu Lys Cys Pro Thr Cys Pro Asp Ala Cys Thr Phe Lys Lys Glu Cys 625 630 635 640 gtg gag tgt aag aag ttt gac cgg gag ccc tac atg acc gaa aat acc 1968 Val Glu Cys Lys Lys Phe Asp Arg Glu Pro Tyr Met Thr Glu Asn Thr 645 650 655 tgc aac cgt tac tgc cgt gac gag att gag tca gtg aaa gag ctt aag 2016 Cys Asn Arg Tyr Cys Arg Asp Glu Ile Glu Ser Val Lys Glu Leu Lys 660 665 670 gac act ggc aag gat gca gtg aat tgt acc tat aag aat gag gat gac 2064 Asp Thr Gly Lys Asp Ala Val Asn Cys Thr Tyr Lys Asn Glu Asp Asp 675 680 685 tgt gtc gtc aga ttc cag tac tat gaa gat tct agt gga aag tcc atc 2112 Cys Val Val Arg Phe Gln Tyr Tyr Glu Asp Ser Ser Gly Lys Ser Ile 690 695 700 ctg tat gtg gta gaa gag cca gag tgt ccc aag ggc cct gac atc ctg 2160 Leu Tyr Val Val Glu Glu Pro Glu Cys Pro Lys Gly Pro Asp Ile Leu 705 710 715 720 gtg gtc ctg ctc tca gtg atg ggg gcc att ctg ctc att ggc ctt gcc 2208 Val Val Leu Leu Ser Val Met Gly Ala Ile Leu Leu Ile Gly Leu Ala 725 730 735 gcc ctg ctc atc tgg aaa ctc ctc atc acc atc cac gac cga aaa gaa 2256 Ala Leu Leu Ile Trp Lys Leu Leu Ile Thr Ile His Asp Arg Lys Glu 740 745 750 ttc gct aaa ttt gag gaa gaa cgc gcc aga gca aaa tgg gac aca gcc 2304 Phe Ala Lys Phe Glu Glu Glu Arg Ala Arg Ala Lys Trp Asp Thr Ala 755 760 765 aac aac cca ctg tat aaa gag gcc acg tct acc ttc acc aat atc acg 2352 Asn Asn Pro Leu Tyr Lys Glu Ala Thr Ser Thr Phe Thr Asn Ile Thr 770 775 780 tac cgg ggc act taa 2367 Tyr Arg Gly Thr 785 6 788 PRT Homo sapiens 6 Met Arg Ala Arg Pro Arg Pro Arg Pro Leu Trp Val Thr Val Leu Ala 1 5 10 15 Leu Gly Ala Leu Ala Gly Val Gly Val Gly Gly Pro Asn Ile Cys Thr 20 25 30 Thr Arg Gly Val Ser Ser Cys Gln Gln Cys Leu Ala Val Ser Pro Met 35 40 45 Cys Ala Trp Cys Ser Asp Glu Ala Leu Pro Leu Gly Ser Pro Arg Cys 50 55 60 Asp Leu Lys Glu Thr Gln Leu Lys Asp Asn Cys Ala Pro Glu Ser Ile 65 70 75 80 Glu Phe Pro Val Ser Glu Ala Arg Val Leu Glu Asp Arg Pro Leu Ser 85 90 95 Asp Lys Gly Ser Gly Asp Ser Ser Gln Val Thr Gln Val Ser Pro Gln 100 105 110 Arg Ile Ala Leu Arg Leu Arg Pro Asp Asp Ser Lys Asn Phe Ser Ile 115 120 125 Gln Val Arg Gln Val Glu Asp Tyr Pro Val Asp Ile Tyr Tyr Leu Met 130 135 140 Asp Leu Ser Tyr Ser Met Lys Asp Asp Leu Trp Ser Ile Gln Asn Leu 145 150 155 160 Gly Thr Lys Leu Ala Thr Gln Met Arg Lys Leu Thr Ser Asn Leu Arg 165 170 175 Ile Gly Phe Gly Ala Phe Val Asp Lys Pro Val Ser Pro Tyr Met Tyr 180 185 190 Ile Ser Pro Pro Glu Ala Leu Glu Asn Pro Cys Tyr Asp Met Lys Thr 195 200 205 Thr Cys Leu Pro Met Phe Gly Tyr Lys His Val Leu Thr Leu Thr Asp 210 215 220 Gln Val Thr Arg Phe Asn Glu Glu Val Lys Lys Gln Ser Val Ser Arg 225 230 235 240 Asn Arg Asp Ala Pro Glu Gly Gly Phe Asp Ala Ile Met Gln Ala Thr 245 250 255 Val Cys Asp Glu Lys Ile Gly Trp Arg Asn Asp Ala Ser His Leu Leu 260 265 270 Val Phe Thr Thr Asp Ala Lys Thr His Ile Ala Leu Asp Gly Arg Leu 275 280 285 Ala Gly Ile Val Gln Pro Asn Asp Gly Gln Cys His Val Gly Ser Asp 290 295 300 Asn His Tyr Ser Ala Ser Thr Thr Met Asp Tyr Pro Ser Leu Gly Leu 305 310 315 320 Met Thr Glu Lys Leu Ser Gln Lys Asn Ile Asn Leu Ile Phe Ala Val 325 330 335 Thr Glu Asn Val Val Asn Leu Tyr Gln Asn Tyr Ser Glu Leu Ile Pro 340 345 350 Gly Thr Thr Val Gly Val Leu Ser Met Asp Ser Ser Asn Val Leu Gln 355 360 365 Leu Ile Val Asp Ala Tyr Gly Lys Ile Arg Ser Lys Val Glu Leu Glu 370 375 380 Val Arg Asp Leu Pro Glu Glu Leu Ser Leu Ser Phe Asn Ala Thr Cys 385 390 395 400 Leu Asn Asn Glu Val Ile Pro Gly Leu Lys Ser Cys Met Gly Leu Lys 405 410 415 Ile Gly Asp Thr Val Ser Phe Ser Ile Glu Ala Lys Val Arg Gly Cys 420 425 430 Pro Gln Glu Lys Glu Lys Ser Phe Thr Ile Lys Pro Val Gly Phe Lys 435 440 445 Asp Ser Leu Ile Val Gln Val Thr Phe Asp Cys Asp Cys Ala Cys Gln 450 455 460 Ala Gln Ala Glu Pro Asn Ser His Arg Cys Asn Asn Gly Asn Gly Thr 465 470 475 480 Phe Glu Cys Gly Val Cys Arg Cys Gly Pro Gly Trp Leu Gly Ser Gln 485 490 495 Cys Glu Cys Ser Glu Glu Asp Tyr Arg Pro Ser Gln Gln Asp Glu Cys 500 505 510 Ser Pro Arg Glu Gly Gln Pro Val Cys Ser Gln Arg Gly Glu Cys Leu 515 520 525 Cys Gly Gln Cys Val Cys His Ser Ser Asp Phe Gly Lys Ile Thr Gly 530 535 540 Lys Tyr Cys Glu Cys Asp Asp Phe Ser Cys Val Arg Tyr Lys Gly Glu 545 550 555 560 Met Cys Ser Gly His Gly Gln Cys Ser Cys Gly Asp Cys Leu Cys Asp 565 570 575 Ser Asp Trp Thr Gly Tyr Tyr Cys Asn Cys Thr Thr Arg Thr Asp Thr 580 585 590 Cys Met Ser Ser Asn Gly Leu Leu Cys Ser Gly Arg Gly Lys Cys Glu 595 600 605 Cys Gly Ser Cys Val Cys Ile Gln Pro Gly Ser Tyr Gly Asp Thr Cys 610 615 620 Glu Lys Cys Pro Thr Cys Pro Asp Ala Cys Thr Phe Lys Lys Glu Cys 625 630 635 640 Val Glu Cys Lys Lys Phe Asp Arg Glu Pro Tyr Met Thr Glu Asn Thr 645 650 655 Cys Asn Arg Tyr Cys Arg Asp Glu Ile Glu Ser Val Lys Glu Leu Lys 660 665 670 Asp Thr Gly Lys Asp Ala Val Asn Cys Thr Tyr Lys Asn Glu Asp Asp 675 680 685 Cys Val Val Arg Phe Gln Tyr Tyr Glu Asp Ser Ser Gly Lys Ser Ile 690 695 700 Leu Tyr Val Val Glu Glu Pro Glu Cys Pro Lys Gly Pro Asp Ile Leu 705 710 715 720 Val Val Leu Leu Ser Val Met Gly Ala Ile Leu Leu Ile Gly Leu Ala 725 730 735 Ala Leu Leu Ile Trp Lys Leu Leu Ile Thr Ile His Asp Arg Lys Glu 740 745 750 Phe Ala Lys Phe Glu Glu Glu Arg Ala Arg Ala Lys Trp Asp Thr Ala 755 760 765 Asn Asn Pro Leu Tyr Lys Glu Ala Thr Ser Thr Phe Thr Asn Ile Thr 770 775 780 Tyr Arg Gly Thr 785 7 7 PRT Artificial Sequence synthetic construct 7 Pro Arg Cys Gly Xaa Pro Asp 1 5 8 4 PRT Artificial Sequence synthetic construct 8 Arg Xaa Xaa Arg 1 9 11 PRT Artificial Sequence synthetic construct 9 His Glu Xaa Xaa His Xaa Xaa Gly Xaa Xaa His 1 5 10 10 4 PRT Artificial Sequence synthetic construct 10 Arg Arg Lys Arg 1 11 27 DNA Homo sapiens 11 gactcagctg aaggataact gtgcccc 27 12 27 DNA Homo sapiens 12 tccttcaggt cacagcgagg tgagccc 27 

We claim:
 1. A method of identifying an inhibitor or enhancer of α_(v)β₃ activity, comprising the steps of: (a) contacting superactivated α_(v)β₃ integrin with one or more molecules; and (b) assaying an α_(v)β₃ integrin activity, wherein reduced α_(v)β₃ activity identifies an inhibitor of α_(v)β₃ activity, and wherein enhanced α_(v)β₃ activity identifies an enhancer of α_(v)β₃ activity.
 2. The method of claim 1, wherein said α_(v)β₃ integrin activity is reduced activity.
 3. The method of claim 1, wherein said α_(v)β₃ integrin activity is enhanced activity.
 4. The method of claim 1, wherein said superactivated α_(v)β₃ integrin is expressed on a cell.
 5. The method of claim 4, wherein said cell is a tumor cell.
 6. The method of claim 4, wherein said cell is an immortalized cell.
 7. The method of claim 4, wherein said cell is a MCF-7 breast carcinoma cell.
 8. The method of claim 4, wherein said cell is transfected with a β3 encoding nucleic acid molecule and an MT1-MMP encoding nucleic acid molecule.
 9. The method of claim 8, wherein said β3 has substantially the amino acid sequence of SEQ ID NO: 2 and said MT1-MMP has substantially the amino acid sequence of SEQ ID NO:
 4. 10. The method of claim 9, wherein said cell is a MCF-7 breast carcinoma cell.
 11. The method of claim 4, wherein said cell is transfected with a nucleic acid molecule encoding a superactivated β3 variant.
 12. The method of claim 11, wherein said superactivated β3 variant has substantially the amino acid sequence of SEQ ID NO:
 6. 13. The method of claim 12, wherein said cell is a MCF-7 breast carcinoma cell.
 14. The method of claim 1, wherein said α_(v)β₃ integrin activity is cell adhesion activity.
 15. The method of claim 14, wherein said α_(v)β₃ integrin activity is vitronectin-binding activity.
 16. The method of claim 14, wherein said α_(v)β₃ integrin activity is fibronectin-binding activity.
 17. The method of claim 14, wherein said α_(v)β₃ integrin activity is adhesion to a function blocking α_(v)β₃-specific antibody.
 18. A superactivated β3 variant, comprising substantially the amino acid sequence of a β3 subunit with a threonine analog at the equivalent of position 69 and a glutamine analog at the equivalent of position 70, wherein, when expressed together with an β_(v) subunit, said β3 variant forms superactivated α_(v)β₃ integrin in the absence of MT1-MMP.
 19. The superactivated β3 variant of claim 18, comprising a threonine at the equivalent of position 69 and a glutamine at the equivalent of position
 70. 20. The superactivated β3 variant of claim 18, comprising substantially the amino acid sequence of SEQ ID NO:
 6. 21. The superactivated β3 variant of claim 20, comprising the amino acid sequence SEQ ID NO:
 6. 